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Tendo Civil Security
- The Ace: In the anime, Rentaro is portrayed as a near-flawless protagonist who possesses many skills and abilities. He's still portrayed as a Pragmatic Hero though.
- Adaptation Dye-Job: His hair is changed to blue in the anime.
- Almighty Janitor: His IP ranking is recorded to be relatively low, yet he's a competent fighter himself. Eventually, his IP ranking was raised to 300 after the events of volume 2 and after the battle against Aldebaran's army it was raised to 210.
- Artificial Limbs: He lost his right leg, right arm, and his left eye protecting Kisara from the Gastrea when they were children and took part of the "New Human Creation Plan" to save his own life.
- Awesome by Analysis: He's fairly intelligent, and can deduce some things based on the evidence he sees, such as figuring out Tina isn't entirely evil because she didn't kill the police officer or Enju despite clearly having the ability to do so.
- Badass Longrobe: Dons Gado's longrobe after the latter dies at some point during the Third Kanto War. He doesn't keep it on for long though.
- Badass Normal: He doesn't have any special powers, yet he is capable of engaging the Gastrea pretty effectively.
- Badass Transplant: His artificial left eye grants him Improbable Aiming Skills, and his Super Varanium right arm contributes to the downfall of Scorpio.
- Be Yourself: This is how Kisara and Rentaro ended up as an Official Couple at the end of volume 6, as well as how the relationship conflict with Kisara was resolved during Rentaro's time as a fugitive. While they both don't agree with each other in terms of their ethics; they respect each other as who they are and their reason of existence, and do not wish to change each other's ways.
- Big Brother Instinct: While Enju is capable of fending off the Gastrea and other threats by herself, Rentaro is very protective of Enju's physical, emotional, and mental well-being. Case in point, he gets really defensive when Enju's identity as a Cursed Child is exposed at her school and tries to search for her when Enju didn't come back home from school. He also shows shades of this towards Tina and other Cursed Children.
- Break the Badass: Honestly, the author figures out a way to break Rentaro down mentally and emotionally in every volume.
- Chick Magnet: Not only that, he also happens to be attractive to the Cursed Children as well, so he's accused of being a bit of a paedophile by some of the other characters.
- Childhood Friends: With Kisara and Kihachi.
- Cyborg: Like Kagetane, Rentaro was also a product of the New Human Creation Plan, with a prosthetic right arm and right leg both made out of Super Varanium, and an artifical left eye which grants him Improbable Aiming Skills.
- Dangerous Forbidden Technique: During the mission to retrieve the Inheritance of the Seven Stars from the Hiruko pair, he injects himself with a specialized strain of the Gastrea Virus in order to further increase the superhuman capabilities he'd gained from his modified Artificial Limbs.
- Deadpan Snarker: Has shades of this, particularly with Enju's unrealistic fantasies such as their romantic relationship.
- Determinator: He has surprisingly strong willpower to the point where he simply doesn't die. Heck, he survived getting rapidly impaled by Kohina's katanas, getting shot repeatedly by Hiruko and falling down a ravine into a river below due to his sheer determination to live.
- Emo Teen: Let's just say that when someone he cares about dies, he goes into a strong moment of angst. He thought of committing suicide when he thought Enju was killed off by Tina Sprout.
- Empowered Badass Normal: Thanks to the Artificial Limbs he has, his physical prowess is on a superhuman level.
- Fatal Flaw: The very fact that he refuses to see anyone suffering is one of the biggest flaws of his utilitarian ethics, so he decided to take the emotional burden rather than letting Kisara, Enju, and Tina put up with the pain. Apparently, this only made him cause more suffering instead of bringing happiness to others, as he has to learn this the hard way in volumes 5 and 6 after he got arrested, with Kisara being forced to marry her former boyfriend, Enju being taken away and forced to pair with a total stranger, and Tina being executed for a crime she didn't commit.
- Field Promotion: He's given the rank of 300 by Seitenshi in episode 7 note , which allows him to outrank Yasuwaki, one of her bodyguards, and allows him access to some higher level secret documents she has.
- For Happiness: Rentaro follows a strict utilitarian ethics where he wants everyone in his life (especially Enju and Tina) to be happy, but he doesn't want people around him to suffer. This is deconstructed in the Fugitve arch where he is willing to sacrifice his own happiness and freedom for Enju's, Tina's, and Kisara's happiness, but it end up backfiring where everyone suffered instead.
- Friend to All Children: The reason he's well-liked among the Cursed Children. He does not see them as vermin, but rather as equals and treats them with kindness. This is also one of the main reasons why he is able to maintain a good Like Brother and Sister relationship with Enju and Tina as well as bringing the happiness into their lives they never had.
- Gun Fu: Incorporates the Tendo style martial arts along with his gun usage.
- Guns Akimbo: He dual wields pistols in episode 7 during an evaluation by Miori.
- The Gunslinger: Uses a Springfield XD pistol to combat the Gastrea.
- Heroic B.S.O.D.:
- Hates Being Alone: Much like Enju, Rentaro cannot imagine his life without Enju, Tina, and Kisara in his life. Not to mention, he brought happiness to the said characters' lives and in return, they made him feel like he belonged there.
- The Hero: The main protagonist of Black Bullet.
- Humans Are Flawed: Has this viewpoint on humanity. While he acknowledges the reality that humanity has done very horrible things towards the Cursed Children, he still has faith that there is a good side in being a human and hopes that humanity can accept Cursed Children as humans.
- I Am Not Left-Handed: During his second fight with Kagetane, he reveals a trump card he's been hiding up till that point. His right arm and leg, along with his left eye, are cybernetic implants just like Kagetane has. Said right arm also becomes incredibly useful against the Stage V Gastrea that shows up after he defeats Kagetane.
- Impaled with Extreme Prejudice: Gets pierced by Kohina's blades from the back. Fortunately he gets better.
- Improbable Aiming Skills: He can hit targets rather far away with just a pistol. Justified however, in that his cybernetic eye allows him to have really good aim.
- I Want My Beloved to Be Happy: Is this towards Kisara and Enju. At least in Enju's case, he wants her to live her remaining 500 days in a happy life. Deconstructed when it comes to Kisara in the Fugitive Arc.
- Japanese Politeness: Averted. He's nearly always condescending to whoever he addresses, be it authoritative figures, allies, or the Cursed Children. On the other hand, he's no less of a Nice Guy.
- Knight in Sour Armor: Well yeah, he's a good guy at heart, but he is more than willing to use lethal force if it means protecting people he cares about, and has a pragmatic approach on things. He supposedly killed Kagetane.
- Knight Templar Big Brother: There are very strong hints of this trope during the Fugitive arch. Volume 5 states that Enju has become his obsession.
- Let's Get Dangerous!: He generally prefers a move civilized resolution to most of the non-Gastrea problems. Unfortunately the antagonists he's up against generally don't want to talk or side with him, forcing him to have to kick their butts. In addition to that, Rentaro generally never goes all out in a fight unless he's ordered to execute the target. This means that unless part of his orders, Rentaro is not going to fight to win.
- Made of Iron: He remains standing and combative despite being shot three times, hit with a "Maximum Pain" attack, and stabbed through the gut with dual swords, multiple times!.
- Mercy Kill: Is forced to put down Kayo Senju when her Gastrea virus exceeded critical value. He does not take this well at all.
- Mistaken for Pedophile: Due to working with Enju, he's constantly accused of being a paedophile. And when he tries to deny it, no one really believes him. Naturally this is also the first thing the Cursed Children in episode 8 ask him when he's trying to teach them at a school he set up with Kisara. Sumire also teases him about this to Tina in episode 9, stating that he's trying to start a harem of young girls.
- My God, What Have I Done?: In volume 5, after rejecting Kisara's help to get him out of jail and telling her to find happiness, he later finds out that his Promoter licensed got revoked, and that Enju has been taken away and forced to pair up with a Promotor named "buddy killer," and Tina was about to be executed for a crime she didn't commit.
- My Parents Are Dead: When Kisara reminds Rentaro about how he is convinced his parents are still alive, he snaps back and instead acknowledges that they both died during the Great Gastrea War.
- The Needs of the Many: A variant. His utilitarian ethics involves sacrificing his own happiness for the sake of others's happiness. His utilitarianism bites him in the ass in the Fugitive Arch.
- Nice Guy: He's willing to help others in need when necessary.
- No-Holds-Barred Beatdown: Is sometimes on the receiving end of one, such as against Kagetane in their first few encounters. He pays them back in kind however, when the opportunity arises.
- Oblivious to Love: For the most part. He does seem to have an interest in Kisara, but never makes a move on her. Sumire teases him about it, and wonders how Kisara is still single. However, it's more of a case of Single-Target Sexuality mixed with Selective Obliviousness, as he is aware that Enju has feelings for him, but ignores it, and he only has feelings for Kisara.
- Official Couple: He gets together with Kisara after volume 6.
- Please Don't Leave Me: A slight variation of this trope at the anime finale, where Rentaro tearfully break down in Enju's lap.Rentaro: I’m afraid, I’m becoming unaffected by the deaths of others... Enju... Please stay by my side, always...Don’t let me go...
- Pragmatic Hero: While he is a good person at heart, he takes a more rational and realistic approach on things, dealing with problems without going into the Anti-Hero category. He's willing to use lethal force against Kagetane as well.
- He also prevents Enju from saving a Cursed Child who stole some food, noting that such action would have resulted in a negative outcome between him and Enju.
- When Rentaro takes the position as commander after Gado was killed off, a fellow civil security officer questions him. Rentaro responds by stabbing said civil security officer in the shoulder, hoping that other civil security officers will discard their fear and instead hate him so that the civil officers' morale will be boosted.
- Red Eyes! Take Warning: When he regenerates his organs with a drug given to him by Sumire, his eyes flash red a few times, but he survives the gamble and doesn't mutate into a Gastrea.
- Red Oni, Blue Oni: Serves as the blue to Enju's red and red to Kisara's blue.
- Relative Button: If you value your life, don't harm a hair on Enju or Tina (or any Cursed Child, for the matter).
- Second Year Protagonist: A sophomore of Magata High School, and The Hero of the series.
- Screw the Money, I Have Rules!: Kagetane attempted to bribe Rentaro with a suitcase filled with cash in order to get him out of poverty and join his evil cause, Rentaro responded by shooting at the suitcase.
- Suicide Mission: He was sent on one by Gado to kill the Gastrea Pleiades in lieu of capital punishment after his adjuvant disobeyed orders.
- Super Soldier: As a result of the New Human Creation Plan that gave him Artificial Limbs, since the project's original purpose was to craft mechanical soldiers to combat the Gastrea before it got shut down.
- Tsundere: A male and subtle example. He feels really uneasy when Enju tries to make romantic moves on him, noting how wrong this kind of relationship would be.
- Tsurime Eyes: Highlighting his seriousness.
- Undying Loyalty: After Enju's status as a Cursed Child is revealed and is left an academic pariah, Rentaro quickly comes to her defense.
- Unwanted Harem: Enju, Tina, and the group of Cursed Children he tries to teach all want to marry him.
- Wake Up, Go to School, Save the World: A student of Magata High School who fights to protect the world from the Gastrea threat.
- What Measure Is A Nonhuman: Averted. While most people typically see Cursed Children as an annoyance, if not a threat, he tries to treat them like normal humans. Unsurprisingly, this makes him more likable to those girls.
- What the Hell, Hero?: Enju asks why Rentaro didn't do anything for the Cursed Child caught stealing food in episode 2. And when she tried to reach out to Enju, he stopped her. She then asks if he's supposed to be a protector, making him feel guilty about it, and causing him to chase after the police as a result. Although to be fair, Rentaro was being realistic in this situation because all of the possible outcomes would have been bad for both him and Enju as it would have put them in a bad light, possibly revealing Enju as a Cursed Child herself.
- The Worf Effect: Suffers from this when fighting against Kagetane. The latter only let him live because he felt Rentaro would be a useful ally to have. And it was only because of a risky gamble with a drug Dr. Muroto gave him that allowed him to defeat Kagetane.
- Would Hit a Girl: Well, normally he wouldn't. But he's forced to during his fight with Tina due to her orders to kill Seitenshi, and for also hurting Kisara and Enju.
- Abusive Parents: Given that she was raised by her abusive foster parents, it's no wonder she turned out the way she did.
- Action Girl: Like most of the other Cursed Children, she's a very capable fighter.
- A-Cup Angst: She felt offended when Rentaro told her that she's flat-chested. She also tells Seitenshi in episode 5 that Rentaro doesn't look at any girls who have smaller breasts than Kisara. Justified though, she is only about ten years old.
- Adorably Precocious Child: Has her moments, particularly with her crush with Rentaro.
- All Love Is Unrequited: She has romantic feelings towards Rentaro. Rentaro does love Enju, but more as a little sister rather than a romantic interest. Besides, Rentaro has shown romantic interest towards his childhood friend, Kisara, anyways.
- All-Loving Hero: One of her trademarks traits. For example Enju is quick to forgive her classmates for turning their backs on her and says she'll continue to protect them. She also later forgave Tina Sprout after the Assassination arch and later become one of her best friends despite the fact that Tina brutally injured her earlier.
- All of the Other Reindeer: Her teachers and classmates in school are revolted by the discovery of her cursed status.
- Animal Motifs: Rabbit. She wears black hairpins with bunny designs and her Girlish Pigtails somewhat resembles long rabbit ears in the manga.
- Antiquated Linguistics: Speaks in an archaic manner for some reason, referring to herself with warawa (妾), a first-person pronoun used by noble and archaic women.
- Badass Adorable: She's one adorable young girl that can kick Gastrea's ass.
- Bad Powers, Good People: Who would have thought a 10-year-old girl born with the Gastrea virus in her blood can be one of the most-kindhearted characters?
- Because You Were Nice to Me: The main reason she warmed up to Rentaro was because he tried to treat her like a normal person. In the backstory, she seemed quite hostile to him when they first met, but after eating some decent food he made, she starts to act less cold towards him.
- Big Brother Attraction: She is very emotionally attached to Rentaro and sees him not only as an older brother figure, but as a romantic interest.
- Blush Sticker: Has brightly colored blushes in her face, but are more visible whenever she's happy.
- Break the Cutie: Numerous times in this series from being a pariah at the school she attends to after her status as a Cursed Child became public knowledge to seeing Rentaro "dying", you really have to feel sorry for this poor girl. She also doesn't take it very well when she sees the bodies of all the girls that were attending the class Rentaro and Kisara were attempting to teach in episode 10.
- Bunnies for Cuteness: Enju has a rabbit theme in her character. Her Gastrea virus in her blood is not only a Rabbit Initiator, she wears black hairpins with bunny designs, her Girlish Pigtails always resembles long bunny ears, her combat style specializes around kicks, and has an energetic and very friendly personality as well.
- Cheerful Child: She always maintain a sunny disposition no matter how bad things are.
- Clingy Jealous Girl:
- Is this towards Kisara in relations to Rentaro's relationship with her.
- In the first episode of the anime, at the end of one day, she asks if he wants to do anything after they're done eating at night. He says he does, and then goes to bed in his room. She immediately goes in there and beats him up for not wanting to take advantage of her.
- Later she gets upset at him for spending some time with Kayo while he attended her injuries.
- She headbutts him in the jaw after he compliments Seitenshi in episode 5 while discussing with her about what she planned to do in the future.
- In episode 9, she, along with the other people he recruited to help protect the breached monolith, interrupt a moment that he was having with Kisara. She angrily accuses him of having groped her just moments before, which he vehemently denies.
- Cute Bruiser: She is quite powerful despite being really young due to the Gastrea virus inside of her.
- Dark and Troubled Past: Volume 7 light novel reveals a lot of Enju's backstory and reveals how she developed a lot of trust issues, yet maintains a Nice Girl All Loving Heroine personality. Enju was adapted by the Aihara family where the former ruler of Tokyo gave money to families who raise and adapt Cursed Children. Unfortunately, many families only adapt the children just for the money, so the policy was abandoned. Enju happens to be one of those children and she suffered a lot of physical and emotional abuse by her foster family. This caused Enju to fought back against her foster family and ran away from home into the outer areas and committed crimes just to survive minus murder (apparently, this caused her to be shot by the police numerous times). She joined IISO as an initiator just to have a better life.
- Dirty Kid: For a 10-year old kid, she likes to harp on quite a bit about how Rentaro has a preference for big boobs.
- Double Standard: Abuse, Female on Male: Any time she beats up Rentaro, it's seen as cute or acceptable. If the situation were reversed, he'd probably be in jail, assuming she didn't kill him first.
- Extremity Extremist: As a 'Model Rabbit' Initiator, most of her power is in her legs and her feet - making kicks her main weapon. About the only time she throws a punch is when she'd inflicting Amusing Injuries on Rentaro.
- Fragile Flower: Only in the anime and manga, she is portrayed as an emotionally sensitive girl who is prone to crying a lot when tragedy strikes her.
- The Friend Nobody Likes: Almost everyone in society, including her classmates and teachers, has expressed dismay about her quirks as a Cursed Child.
- Genki Girl: Gets chipper, energetic, and happy really easily.
- Girlish Pigtails: Wears two twintails that resemble long, drawn down, bunny ears. This is more noticeable in the manga and light novel adaptations.
- Good Is Not Soft: While she's a sweet, kind-hearted young girl at heart, she isn't hesitant to kick someone's ass when necessary whether if it's the Gastrea or some villain.
- Hates Being Alone: She can't stand loneliness after being alone for most of her life. You can easily imagine the emotional trauma during volumes 5 and 6 when she was forcefully taken away and separated by the IISO and forced to be paired with a total stranger named "buddy killer."
- The Heart: She serves as the moral center for Tendo Civil Security company.
- Hero with Bad Publicity: Her classmates and teachers distrust her now that her status as a Cursed Child became public knowledge.
- Humans Are Flawed: Much like Rentaro, Enju holds this viewpoint. She acknowledges the harsh reality on humanity's Fantastic Racism against the Cursed Children and feels that there is a good side in humanity and hopes humanity can accept her kind. Hence, this is one of the reasons why she continues fighting against the Gastrea, because she loves everyone unconditionally.
- I Just Want to Have Friends: One of the main reasons why Enju was so hesitant in transferring schools. When her status as a Cursed Child becomes public knowledge, she says that she still loves them and is willing to protect them.
- Incorruptible Pure Pureness: Being one of the most pure hearted and most kind-hearted characters in the series, she is not easily swayed by any form of evil manipulation such as the Hiruko pair's attempts to have Rentaro and Enju join their evil cause. The only thing that is "corrupting" her is her high corrosion rate.
- Kick Chick: Most of her combat abilities involves a lot of kicking. Justified, as the boots she wears have the tip of her boots and soles made of Varanium and the fact that she's a Model Rabbit Initiator, makes kicking, jumping, and agility her speciality.
- It's also implied the reason why she only fights with her boots and kicks is because she wants to fight the Gastrea without having to kill people.
- Kid Hero: In contrast to Rentaro who is older then her, Enju is much younger and more of a traditional hero.
- Little Sister Heroine: Rentaro treats Enju like a little sister to him rather than just an initiator. It can also be a Deconstruction to this trope, as her Precocious Crush not only serves an annoyance to Rentaro, but her high corrosion rate serves as an emotional burden to him as well.
- Locked Out of the Loop: At the end of episode 4, Rentaro tells her that her body corrosion rate is at 24.9%, which she mentions barely changed at all. But as they walk down the street, a screen reveals her actual corrosion is at 42.1%, and she only has about 7.2% left before she succumbs to turning into a Gastrea.
- It's also highly implied that Enju has no idea that Cursed Children will eventually turn into a Gastrea or die if the erosion rate is left unchecked (even though she knows the erosion rate concept).
- Morality Chain: She's one of the reasons why Rentaro doesn't take a darker path or fall into despair.
- Nice Girl: No matter how much she is marginalized, she always sweet, friendly, and kind-hearted towards everyone she meets.
- To demonstrate how much of a Nice Girl Enju is, after her status as a Cursed Child became public knowledge in the school she attends to, she said that no matter how much her classmates and teachers distrust her, she will always love them and will fight for them.
- In episode 7, she's such a Nice Girl that she even forgive Tina and befriended her despite Tina severely injuring Enju and sparing her life.
- She helps tend the wounds of many civil security officers in episode 11/the beginning of volume 4 and was given a nurse's hat for her kind efforts.
- Pint-Sized Powerhouse: Standing 145 cm, she's a competent fighter.
- Plucky Girl: Regardless of how she and other Cursed Children are ridiculed, she maintains her strong optimism no matter what happens to her.
- The Pollyanna: She's probably one of the most optimistic characters in a very dark world and is able to cope with tragedies around her easily. Sumire mentions that Enju is mentally strong despite the abuse and trauma she received from society.
- The light novels mentions that she is emotionally strong and acts more mature than a typical 10-year-old. This is due to the abuse she has suffered when living in the Outer Districts that allowed her to be a emotionally strong and independent young girl and have a better understanding of the world around her while maintaining her optimistic beliefs at the same time.
- Power of Trust: One of her biggest issues is her hard time trusting others. However, she does eventually maintain a good relationship with Rentaro.
- Precocious Crush: There are some hints of this with Rentaro.
- Rapunzel Hair: Spots very long hair, especially when not wearing her hairpins that shape her iconic long twintails.
- Screw This, I'm Outta Here!: When she was still young, she left her foster parents due to their abuse towards her.
- Silk Hiding Steel: Despite her tendency to cry a lot when tragedy strikes, Enju happens to be emotionally and mentally strong, and is more wiser than many 10-year-olds.
- Tareme Eyes: To highlight her Wide-Eyed Idealist and Nice Girl personality.
- Technical Pacifist: While she's not hesitant on using brute force when fighting bad guys and the Gastrea, she absolutely refuses to kill another human being. Case in point, she's very hesitant on mercy killing an infected man in episode 1 before the said man turned into a Gastrea.
- Discussed by Kayo Senju stating that Enju isn't the kind of girl who is willing to kill another human being when discussing how the former was ordered by her Promotor, Shougen Ikuma, to kill a Initiator-Promotor pair because Shougen refuses to share the rewards.
- Also, her Dark and Troubled Past while living in the outer districts shown that she had to commit various amounts of crimes just to survive. The only crime she never committed is murder.
- Tearful Smile: Whenever she's reunited with Rentaro and in the anime finale.
- Tender Tears: Prone to breaking down in tears a lot due to her kind-hearted and sweet sensitive nature of her personality.
- Typhoid Mary: She's highly unaware that she is slowly turning into a Gastrea monster or dying.
- Undying Loyalty: To Rentaro, to the point that she has Precocious Crush moments with him.
- Wide-Eyed Idealist: She always maintain her optimistic personality no matter how bad things are. Unfortunately, she's not aware of the eventual fate she may suffer like most Cursed Children.
- Wise Beyond Their Years: In the light novels, she's portrayed to be more mature than most 10-year-old girls and an emotionally strong and independent young girl.
- You Are Not Alone: After the doctor that worked on Rentaro in the past explains to him that he at least knows where he came from, whereas Enju was abandoned and confused as to where she stands in the world, he tells Enju that regardless if she is considered an outsider, he would still be by her side.
Enju: "It’s all right, Rentaro. You and I will always be together, forever and ever.”
- Enju pulls this trope out with Rentaro in the finale of episode 13/volume 4 where Enju lies on Rentaro's back when he was laying on her lap crying.
Voiced by: Yui Horie (Japanese), Christina Kelly (English)The president of the Tendo Civil Security Company. Her parents were killed by the Gastrea and have family issues (particularly her grandfather).
- Absurdly Sharp Blade: Her katana slices off the front end of several barrels on an assassin's gatling gun in episode 6. She also cuts through a rather large Gastrea in episode 13.
- Abusive Parents: Her parents were killed by her grandfather. The effects of her grandfather's "parenting" are obvious in her personality.
- Action Girl: She can be an effective fighter when the situation calls for it.
- Anti-Hero: She's doing what is best for the Tendo Civil Security, Rentaro, and Enju. However, the fact that she holds a strong grudge against her own family and her Pay Evil unto Evil attitude makes her a flawed character. Her dark side of her anti-heroic personality is highlighted further in the anime when she killed her own brother rather than sparing his life and takes joy in killing him, thus causing Rentaro to be worry on what she will become.
- Authority Equals Asskicking: She's a swordswoman and is the president of a Civil Security Company.
- Badass Adorable: A highschool girl who not only runs a Civil Security Company, but also capable of kicking lots of ass with her katana.
- Be Yourself: This is how Kisara and Rentaro ended up as an Official Couple at the end of volume 6, as well as how the relationship conflict with Kisara was resolved during Rentaro's time as a fugitive. While they both don't agree with each other in terms of their ethics; they respect each other as who they are and their reason of existence, and do not wish to change each other's ways.
- Boobs of Steel: A recurring gag with Kisara often involves her large breasts, often a source of Enju's jealousy.
- Broken Bird: What happened to her at the end of volume 6 in regards to the events that happened in volume 5 and 6 (in addition to losing her parents). She mentions that a broken body can be healed, but you can never heal a broken soul.
- Clingy Jealous Girl: This starts to crop up when Miori Shiba, the student council president at Rentaro's school, and daughter of the CEO that sponsors his equipment, pays him a visit at the same time as her in episode 5. Kisara also doesn't like that Miori keeps trying to snag him away, not just romantically, but also to work directly for her company. Both girls end up making verbal jabs at each other while eating at his apartment. In episode 6, she also doesn't like it when Rentaro is alone with Miori in the student council office.
- Childhood Friend Romance: With Rentaro.
- Cool Big Sis: A bit of one to Enju, and later, to Tina.
- Dark and Troubled Past: Her parent's death has caused to hate her own family heritage and take a darker turn of her personality.
- Deadpan Snarker: Particularly when it comes to Rentaro.
- Glass Cannon: Her remarkable swordsmanship and skills makes her a remarkable fighter. However, the fact that she has kidney problems prevents her from fighting in prolonged periods of time and put a strain to her body.
- Heroes Prefer Swords: She uses a katana as her Weapon of Choice.
- If You Kill Him, You Will Be Just Like Him: One of Rentaro's concern about Kisara's dark path of revenge against her family is that if she continues her path of revenge, she'll end up as bad as the family members she killed.
- Ill Girl: It's revealed that Kisara has a severe kidney health problem, thanks to the Gastrea attack that killed her parents.
- Judge, Jury, and Executioner: Served this during the duel against Kazumitsu and when killing him.
- Kick the Son of a Bitch: She cuts down Kazumitsu in their duel.
- Master Swordswoman: She is capable of wielding a katana.
- Official Couple: She becomes lovers with Rentaro after the end of volume 6.
- Pay Evil unto Evil: Firm believer of this. Rentaro fears she may end up being just as evil as the people she's trying to kill.
- Reasonable Authority Figure: She generally does what she can to help Rentaro out on his missions. Due to their strained finances, said help usually doesn't amount to much other than him not wanting to disappoint her, though that's usually enough to get him to accomplish the mission.
- Revenge Before Reason: She wants revenge against her Tendo family clan for the death of her parents.
- Sailor Fuku: Her default outfit both for school and at work.
- School Uniforms Are the New Black: Usually wears her school uniform on most occasion.
- She Who Fights Monsters: Kisara starts down this slippery slope in episode 13 after she brutally slices off her older brother's legs with an attack that ultimately kills him. She seems a little too ecstatic about having just murdered someone, regardless if it was justified, and Rentaro fears he may have to fight her someday if she continues down this path.
- She's Got Legs: Her long legs are accentuated with her knee-high socks.
- Tsurime Eyes: Like Rentaro, Kisara spots this to highlight her serious and Anti-Hero side.
- Yandere: Played for Laughs:
- In episode 5, she attacks Miori after the latter gets too close to Rentaro.
- In episode 6, after he goes to the student council office to meet with Miori, Kisara tells him that she's going to throw a tear gas canister in there, and then she's going to shoot Miori twice in the chest, and once in the head when she comes out of the office.
- You're Not My Father: She is unwilling to forgive her grandfather and her clan in general due to her parents' death and she refuses to acknowledge her relationship with them.
- Achilles' Heel:Bright flashes or light temporarily blinds her as evident with the discharged flash bang (or the sudden flash of light from a Molotov cocktail in the light novels). It contributes to her defeat at Rentaro's hands.
- Action Girl: She can put up quite a fight, as several characters and a cop finds out.
- Almighty Janitor: Even after having her initial IP rank of 98 revoked and being assigned a rank of 9,200 after forming an IP pair with Kisara, she's still a very competent Initiator.
- Animal Motif: Owls. Lampshaded by Rentaro, who notes that Tina, as a Model Owl, is vulnerable to bright flashes or light which blind her temporarily.
- Arc Villain: One of the main antagonists of the second volume, working under Ayn Rand's orders to assassinate Seitenshi. She gets out of this after she is defeated by Rentaro.
- Ascended Extra: She later plays a larger role in volume 3 and 4.
- Badass Adorable: Like every other young girl in this series. In episode 7, Miori mentions that Rentaro's fighting power is about 2200%. Meanwhile Enju's is rated at about 8600%, while Tina's is a mind-boggling 12,900%.
- Because You Were Nice to Me: She was really soft on Rentaro when they first met because he talked to her normally and bought some food for her later. Heck, she spares Enju's life as well.
- Beware the Nice Ones: A cop finds this out the hard way when he innocently tries to help her while she was on her way to a mission. Fortunately for him he's stated to have survived, though his squad car gets totaled.
- BFG: She uses a gatling gun in one of her missions to kill Kisara.
- Blush Sticker: Like Enju, Tina has brightly colored blushes in her face that are mostly visible whenever she's happy.
- Child Soldier: Was the product of the mechanized soldier/Cursed Child hybrid program.
- Cloudcuckoolander: Can be a bit of an airhead sometimes.
- Cold Sniper: Her choice of weaponry in combat, though she does use combat drones for close encounters.
- Cute Bruiser: Like many of the Cursed Children, she's pretty strong and powerful physically. In fact, it's stated that her combat abilities is far superior than Enju's.
- Defeat Means Friendship: After being defeated by Rentaro, she decided to join the Tendo Civil Security Company. Noting that Rentaro has treated with kindness while her employer views her as expendable, she decided to start a new life with the former and made good friends with Enju.
- Desperately Looking for a Purpose in Life: She wanted to make her own life meaningful and wanted to have a reason to exist as a Cursed Child. Thanks to some of Rentaro's encouraging words, she decided to find her own meaning in life by joining the Tendo Civil Security Company.
- The Dragon: Initially to Ayn Rand, where she worked under his orders to assassinate Seitenshi.
- The Dreaded: She has an IP rank of 97. Seitenshi tells Rentaro that anyone ranked 100 or higher are considered deadly. He finds out about this after he sent Enju off to pursue her, and later tries to phone her, and though it gets picked up, Enju doesn't answer it. He assumes the worst has happened.
- Easily Forgiven: Despite being ordered to take out Seitenshi, she is actually forgiven by the person she was trying to assassinate. Kisara and Enju also don't seem to hold any grudges against her despite Tina harming both of them before.
- Empty Shell: The reason she was working with Ayn Rand was because she felt that her life was completely empty, and by working with Ayn Rand establishes some meaning in her life. Fortunately, she decided to find her own reason of existence by joining the Tendo Civil Security Company.
- Friendly Sniper: Sure, she's a sniper, but she's also a Nice Girl as well. More evident after joining Tendo Civil Security.
- Genius Ditz: While she can act like an airhead from time to time, she can be very smart and clever as well.
- Hair of Gold, Heart of Gold: Despite Tina being ordered to kill Seitenshi, Tina is one of the most kindhearted characters at heart tied with Enju.
- Heavy Sleeper: She claims she's most active at night, and when Rentaro first runs into her during the day, he has to save her from some thugs who accost her after she accidentally hits one of them on her bicycle. Even taking caffeine pills doesn't help much.
- Heel–Face Turn: Not like she has a choice anyways. Fortunately it doesn't bother her as she likes Rentaro and Enju.
- Heroic B.S.O.D.: Suffers from a temporary one in episode 6, after she finds out that Rentaro was the one guarding Seitenshi and foiled her assassination attempt.
- Innate Night Vision: Due to her being a Model Owl, she has very strong night vision.
- Just Following Orders: The initial reason she was doing bad things. She tells Rentaro that by doing these things, it gives her life meaning. Rentaro calls her sad, but later mentions he would try to help give her a happier life without having to kill people.
- Little Sister Heroine: Like Enju, Rentaro sees Tina like a little sister.
- Nice Girl: Like Enju, Tina happens to be a relatively friendly girl at heart. Her kindhearted personality also plays a role into Rentaro's realization that Tina isn't an evil person at heart and is forced to assassinate people against her own will.
- Nothing Personal: As Ayn Rand's Initiator, she bears no mal intent towards her opponents, and insists that she's only doing as her master orders her to.
- Obfuscating Stupidity: When Rentaro first runs into her, she's very sleepy and still wearing pajamas despite it being broad daylight. She also seems dazed and confused, causing him to worry about her a little bit, and later gives her his phone number in case she needs anything. However, it appears to have largely been an act, and she seems quite intelligent once she calls her handler and lets them know she's infiltrated the Tokyo Area.
- One Note Chef: Tina made pizza for Rentaro and Enju to eat for dinner. When she was asked what other foods she can make, she stated the pizza is all she can make.
- Only a Flesh Wound: Suffers from a shot to her abdomen by Takuto in episode 7. However, the latter realizes non-varanium bullets won't kill her outright, and wonders how many lead bullets it would take to eliminate her. He's stopped by Seitenshi before he can put that theory to the test.
- Parental Abandonment: Though in this case it's because her parents died, as she reveals to Rentaro in episode 6 after he spends some time with her.
- Phenotype Stereotype: Subverted. She does have the blue eyes, blonde hair appearance of an American. However, her personality is completely opposite from the typical American stereotype from the Japanese viewpoint.
- Precocious Crush: Like Enju, Tina happens to be emotionally attached to Rentaro and wishes to marry him.
- The Quiet One: She doesn't really talk much with people.
- Reluctant Warrior: She only kills when she absolutely has to, or is ordered to do so in the case of her first boss. Otherwise she tries to use non-lethal, albeit painful, methods of disabling non-targets. This is ultimately what saves her and gives her a better opportunity in life after she is stopped by Rentaro.
- Small Girl, Big Gun: She uses a rather large sniper rifle.
- Smarter Than You Look: She can be quite cunning despite her ditzy personality, more so then Enju.
- Wise Beyond Their Years: Even moreso than Enju.
Promoters & Initiators
Pairs which consist of a Cursed Child and an adult supervisor, formed to combat the Gastrea threat.
- Badass Adorable: The Initiators are all Cursed Children who can hold their own ground against the Gastrea.
- Badass and Child Duo: IP pairs consist of a Cursed Child as the Initiator, and an adult supervisor as the Promoter.
Voiced by: Rikiya Koyama (Japanese), Jay Hickman (English)
A former promoter of a Civil Security company before his license was revoked due to excessive killing. Held an IP rank of 134.
- Arc Villain: The main antagonist of the first volume, stirring chaos in the Tokyo Area with his daughter under Kikunojo's orders to further destroy the Cursed Children's reputation.
- Artificial Limbs: Like Rentaro, he took part on the "New Human Creation Plan."
- Ax-Crazy: Is perfectly okay with people getting killed for the sake of making sure people like him and Rentaro are needed to fight the Gastrea.
- Badass Finger Snap: A simple snap of his fingers enables his Deflector Shield.
- Badass in a Nice Suit: The only human enemy Rentaro faces who actually is a threat.
- Blood Knight: He enjoys fighting and killing to the point his licence as a promoter of a Civil Securiry Company was revoked due to excess killing on his point.
- Casual Danger Dialogue: He casually talked to his daughter on his cell phone while constantly avoiding Rentaro's kicks. And when Rentaro does manage to lay a hit on him via a kick to his face, bending his neck backwards, Kagetane snaps it back into place and finishes the conversation on his phone unfazed.
- Coat, Hat, Mask: Kagetane wears a combination of a tailcoat, a top hat, and a white mask. His description in the first light novel describes him with such.
- Cool Mask: Wears a white mask which sports an exaggerated smile.
- Cop Killer: Has no problem killing police officers if they get in his way.
- Cyborg: His internal organs have been replaced with Varanium cybernetics as a result of the New Human Creation Plan.
- Deflector Shield: Not only does his Imaginary Gimmick halt incoming projectiles, it can also reflect them back.
- Disney Villain Death: Rentaro knocks Kagetane into a river in episode 4 after finally managing to defeat the latter. And episode 11 reveals he's Not Quite Dead, though he also isn't actively opposing Rentaro at the time either.
- Dynamic Entry: Very fond of this. In the manga, he appears out of nowhere by sitting on a chair.
- Dystopia Justifies the Means: Kagetane's motivation is to start another Gastrea war to ensure that the world will always be filled with chaos and always need people like him, the Cursed Children, and Rentaro.
- Enemy Mine: Assists Rentaro with his Suicide Mission, and eventually joins him in the Third Kanto War to combat Aldebaran's forces.
- Even Evil Has Loved Ones: He seems to genuinely care about his daughter, not that that takes away from his evil.
- Evil Laugh: Enjoy this trope a lot.
- Evil Is Hammy: In the manga and anime adaption, he's portrayed to be a bit more overdramatic.
- Expy: Lampshaded in the anime. When he joins Rentaro against the Gastrea and Aldebaran, Rentaro gives everyone a card motif. Kagetane's though? The Joker.
- The Faceless: He's always seen wearing a white mask.
- For the Evulz: There really is no reason for the stuff he does besides enjoying it.
- Gratuitous English: "Hallelujah!"
- Guns Akimbo: He dual-wields two custom Beretta handguns each with a bayonet attached below the barrel. They have names: "Spanking Sodomy" and "Psychedelic Gospel".
- Hero Killer: He nearly kills Rentaro, and he definitely kills quite a few other characters before being stopped by Rentaro. He also killed Shogen though he wasn't exactly a hero.
- Humans Are Bastards: In a stark contrast to Rentaro's and Enju's Humans Are Flawed, Kagetane feels that humanity is irredeemable due to their racism against Cursed Children and feels that the world is meaningless.
- Impossibly Cool Weapon: His signature bayonet-bladed silver gun.
- Improbable Aiming Skills: He shot down three officers behind him without even turning around to face them.
- Lack of Empathy: Makes it very clear that he has little regard for other people. The only person he seems to genuinely care about is his daughter Kohina.
- Luckily, My Shield Will Protect Me: His Imaginary Gimmick protects him the first few times he's seen using it, as seen in episode 2 when many shots are fired at him, only for him to stop every single bullet, and then deflect them back to the shooters. Rentaro then reveals his cybernetic right arm, which is able to punch through said barrier due to it being made of Varanium.
- Nice Hat: Wears a top hat.
- Not Quite Dead: Was believed to have been killed by Rentaro, but the Third Kanto War Arc proves he is alive and well.
- Not So Different: He thinks him and Rentaro are this. He says that they are both much stronger than an average person and due to that power, they have thought of using force to get their way. The only difference between him and Rentaro is that he listens to his vicious thoughts.
- Offscreen Teleportation: Kagetane seems to be an accomplished expert of this. In the first volume of the light novels, he appeared right in the middle of a meeting sitting on a chair without anyone noticing. Though he did say he came through the front door, albeit by force.
- "The Reason You Suck" Speech: Calls Seitenshi a useless ruler.
- Red and Black and Evil All Over: The colors of his suits vary from red to black, but he's still wicked all the same.
- Starter Villain: He's the first antagonist that Rentaro and Enju encounter in the series.
- Straw Nihilist: Sort of, he mentions to Rentaro that their purpose in life is mosttly because society is dependent on people like him and Rentaro and once society no longer needs them, then there is no purpose for the Cursed Children and civil securities. This is why Kagetane really wants Rentaro to join his cause of starting another Gastrea war.
- Super Soldier: Even more so than Rentaro, since almost all of Kagetane's body is composed of Varanium cybernetics.
- Token Evil Teammate: Becomes this after he joins Rentaro and the others in stopping the Gastrea from penetrating any further into Tokyo. Due to him having killed many others prior to this, he is deeply mistrusted by virtually everyone, and Rentaro only puts up with him because he and Kohina saved his life.
- Troll: Likes to piss everyone off as much as possible.
- Villain Has a Point: As the series progresses and Rentaro sees more atrocities committed against Cursed Children, it's very hard not to believe that Kagetane was right about his beliefs that Humans Are Bastards that are not worth saving.
- Villainous Rescue:
- Saves Rentaro from some Gastrea dogs in Episode 11, even provides him with bandages, antibiotics and food. But for obvious reasons, Rentaro is highly mistrustful of Kagetane's motives and has his gun pointed at the latter for quite some time even as he's patching himself up.
- Saves Rentaro again in Episode 12 after one of the Cursed Children fires a shot at him, blocking the bullet from hitting Rentaro, while Kohina rushes to the girl, and says that if she attempts to move the former would simply cut her head off.
- Wake-Up Call Boss: He's the first major antagonist Rentaro faces off against, and is quite formidable compared to the generic Gastrea monsters he's fought up to that point. In comparison with the other enemies Rentaro faces too, he gave Rentaro one of the hardest fights yet in the series.
- Why Don't You Just Shoot Him?: Zigzagged. He does in fact kill two police officers by shooting them when Rentaro first runs into him. And later he also shoots many other people at a meeting. However, when fighting Rentaro, he seems to prefer melee combat, most likely because he wants to test the latter's resolve and strength.
- We Can Rule Together: Hiruko is very interested in Rentaro and offers him the chance to join his cause on more than one occasion.
- Well-Intentioned Extremist: He certainly tries to paint himself as a good guy, but Rentaro doesn't believe any of it due to the brutal methods he tends to employ, along with trying to bring more Gastrea invasions while the latter is trying to prevent them.
- What Happened to the Mouse?: He and his daughter aren't heard from after the Third Kanto War.
- Wicked Cultured: A very sharply dressed villain.
- Would Hurt a Child: Once attempted to kill Enju, forcing Rentaro to take the bullet.
- Yellow Eyes of Sneakiness: His yellow eyes can occasionally be seen during close-up shots of his mask.
Voiced by: Aoi Yuuki (Japanese), Krystal LaPorte (English)
Kagetane's daughter and a Cursed Child. She serves as a Model Mantis Initiator to Kagetane. Held an IP rank of 134.
- Adaptation Dye-Job: In the light novel series, she wears a black dress and has black hair. The anime design gives her dark blue hair and dark blue dress.
- Affably Evil: Kohina often acts polite, make proper introductions to the victims she is going to kill, and ask her father permission to commit murder on a particular person before she can do so.
- Animal Motifs: To a Praying Mantis. Her two short swords invoke the claw-like pincers of one.
- Ax-Crazy: Despite looking like a typical cute girl, she has a tendency to talk about killing people and severing limbs as if it was normal dialogue for a young child.
- Bad Powers, Bad People: As opposed to Enju's Bad Powers, Good People.
- Creepy Child: Her smile just makes it creepier.
- Cute and Psycho: She can appear innocent at first until she starts killing people.
- Cute Bruiser: She's just as deadly in combat as Enju and Tina.
- Cute Is Evil: She happens to be Kagetane's daughter and a mass murdering psychopath. Doesn't make her less cute in any form. The anime character design highlights her cuteness further.
- Daddy's Little Villain: Kagetane is raising her to be quite an effective killer.
- Dark Is Evil: Wears dark coloured clothes and is one of the main villains.
- The Dragon: To her father Kagetane.
- Dual Wielding: Uses a pair of Varanium short swords in combat.
- Enemy Mine: Joins Rentaro in the Third Kanto War to combat Aldebaran's forces.
- Enfant Terrible: She's very murderous and psychopathic.
- Red Eyes! Take Warning: Her red eyes look different to the common Cursed Child ones, but it only enforces her creepiness.
- Undying Loyalty: To her father.
- What Happened to the Mouse?:
- After her father is beaten, Kohina just disappears after Rentaro leaves. Episode 11 reveals that Kagetane didn't quite die, and she's seen with him again, this time helping Rentaro.
- She and her father aren't heard from after the Third Kanto War.
- Wicked Cultured: Wears a fancy black dress in combat.
- You Gotta Have Blue Hair: In the anime, she has blue hair.
- Your Answer to Everything: Cutting up others.
Voiced by: Hiromichi Tezuka (Japanese), Andrew Love (English)
A battle-crazed Promotor for a Civil Security Company.
- Asshole Victim: He was rather rude and also killed his teammates in an attempt to not have to share the rewards with them. He gets exactly what he deserves thanks to Kagetane.
- BFS: Use a giant sword in combat.
- Blood Knight: He always thirst for a good fight, which is why he refuses to back down on the fight against Kagetane even though he has virtually no chances of winning the battle or have a high chance of getting killed.
- Character Death: He is killed by Kagetane in the duel between them.
- Cool Mask: Wears a face scarf which covers his mouth.
- Dumb Muscle: Let's just say he's isn't really that smart.
- Hoist by His Own Petard: His own sword is used by Kagetane to stab him in the back and killing him shortly after running into Rentaro and Enju.
- Impaled with Extreme Prejudice: How Kagetane runs him through with his own sword.
- Jerkass: He acts like a total asshole in the light novel series. In the manga, however, toned down his character and portrayed him more like a Jerk with a Heart of Gold.
- Rated M for Manly: He's a well-built Promoter with an IP rank of 1,584.
- Red Oni, Blue Oni: The red to Kayo's blue.
- Tattoo as Character Type: Spots tattoos all over his body, showing his "tough guy" image.
Voiced by: Megumi Han (Japanese), Hilary Haag (English)
Shougen Ikuma's Model Dolphin Initiator and a Cursed Child with an IQ of 210, but ill-suited for front-line battles.
- And Then John Was a Zombie: Kayo soon becomes a Gastrea.
- Badass Bookworm: She has an IQ of 210 and is quite smart for a 10-year-old girl.
- Because You Were Nice to Me: The reason she decided to stay behind and fend off a swarm of Gastrea.
- Boom, Headshot: How Rentaro Mercy Kill her to end her pain and suffering from the Gastrea virus.
- Character Death: She is killed by Rentaro to stop her from turning into a Gastrea.
- Cute Bruiser: Like any Cursed Child, she's capable to kicking a lot of ass. She fought off against a horde of Gastrea, but it doesn't stop her from retreating since she's willing to accept fate.
- Face Death with Dignity: She is willing to accept death as her own fate when the Gastrea virus is overwhelming her body.
- Famous Last Words: "Rentaro-san, I think that next….there’ll be countless trails awaiting you. If you ever lose direction, get lost in the darkness, please follow the direction of your heart………light…….follow the light…….Rentaro………..please save…………………….this world."
- Go Out with a Smile: She tries to go for this when talking to Rentaro for the final time. Deconstructed; Rentaro doesn't take it well when he has to Mercy Kill her.
- Heroic Sacrifice: She accepted her eventual fate of most Cursed Children will turn into Eldritch Abomination and wanted to save Rentaro's life, feeling that he can make a greater change and save the world.
- I Cannot Self-Terminate: She was slowly becoming a Gastrea after fending off a swarm of Gastrea, but she was unable to commit suicide since she lost her arm and a leg during the fight, so Rentaro has to Mercy Kill her.
- I Lied: In episode 4, she attempts to Hold the Line for Rentaro, so that he can focus on stopping Kagetane. She assures him that she would run if she found herself at a disadvantage against the Gastrea approaching them. After he defeats Kagetane, Rentaro finds a lot of dead Gastrea, and a severely wounded Kayo, who held out till the very end despite what she claimed earlier about running away.
- Let Them Die Happy: When Kayo asks Rentaro if Shougen is alright, Rentaro responded that he is fine. Unfortunately, Shougen was killed off earlier and Rentaro wanted Kayo to die happily.
- Locked Out of the Loop: When Rentaro finds her at the end of episode 4, she asks how Shougen is doing. He says that he's fine, and she's thankful for that. However, he just lied to her to avoid having Shougen's death put more of a strain on her body, as Rentaro sees him right before he dies from getting impaled with his own sword.
- Kill the Cutie: She's an adorable girl, but dies via a Mercy Kill
- Mercy Kill: When the first signs of her turning into a Gastrea shows up in her severed arm, she begs Rentaro to let her die as a human. Unfortunately all he could do was kill her quickly to avoid having her become a Gastrea.
- One-Man Army: She's actually quite strong enough to fend off multiple Gastrea in an area. Unfortunately, the Gastrea virus in her body overwhelmed her and she started slowly to become the Gastrea.
- Red Oni, Blue Oni: She's the blue to Ikuma's red.
- Shotguns Are Just Better: Her primary weapon.
- The Smart Girl: Has an IQ of 210 to enforce that.
- Smarter Than You Look: Subverted, she's quite smart, but she's unable to identify the stages of the Gastrea virus. A bit justified there though, she's just a kid.
- These Hands Have Killed: When hunting for Kagetane, she tells Rentaro that she was ordered by Shougen to kill another pair hunting the former because the latter didn't want to share the reward with anyone else. She mentions shaking in her hands as she did it, but says she'll get over that. Rentaro immediately tells her that she should never take killing someone so lightly, because otherwise they'll get used to it. While she says she could come up with reasons against that, she also tells him that she believes him.
- The Stoic: She isn't overly emotional even when the Gastrea virus in her body was slowly consuming her.
- Too Good for This Sinful Earth: A young girl who succumbed to the Gastra virus, and had to be mercy killed.
- Wise Beyond Her Years: She's very smart and insightful for a young girl at her age and is highly aware of her eventual fate.
Voiced By: Shin-ichiro Miki (Japanese), Mike Yager (English)Senior disciple of the Tendo style martial arts, Rentaro's senior and old friend. Joined Rentaro's team during the battle against Aldebaran's army.
- Empty Shell: Was this after he was kicked out of the dojo and before meeting Midori.
- Heroic Sacrifice: He sacrifices himself to activate the bomb buried into Aldebaran, resulting in him and Aldebaran getting blown to pieces.
- Men Don't Cry: Though his words shake and he's clearly upset, he doesn't shed a single tear when Midori dies.
- Nice Guy: While he's introduced fighting another civil officer, he's actually quite a nice guy. Even Rentaro seems to have gotten along with him before he left the dojo they trained together at.
- Nice Hat: Wears a black visor hat.
- Not Quite Dead: He was retrieved by Saitake's organization, but he lost all of his limbs, hair and 70% his body was covered burnt.
- Not So Stoic: While visibly upset over Midori's death, he doesn't shed a tear over it.
- Sempai/Kohai: Rentaro and Kisara both think of him as a Sempai and look up to him.
- The Stoic: Has an overall calm and collected disposition.
- We Hardly Knew Ye: In the anime at least, he doesn't have a lot of screen time. Fortunately he's one of the good guys, and both Rentaro and Kisara respect him highly despite him leaving the dojo a short while back due to him working on an unconventional fighting move.
- Absurdly Sharp Blade: Well, it's her claws, but she does cut an assault rifle into pieces when she slashes it with them.
- Badass Adorable: As with any other Cursed Child working as an initiator. Heck, she spots cute cat ears and is a Model Cat Initiator as well.
- Boom, Headshot: Suffers this fate when she shoots herself in the head in a remote area to avoid burdening the surviving Security officers in episode 12.
- Braids of Action: Keeps her fluffy white hair tied up over the shoulder in one of these.
- Cat Girl: Doesn't have the tail (which Enju and Yuzuki attempted to confirm by pulling her skirt down), but does sport some cat ears, which she hides under her witch hat.
- Cute Bruiser: As with many Cursed Children working as Initiator. Heck she destroyed a criminal's assault rifle and avoided all bullets without a single scratch.
- Driven to Suicide: During the second battle she was caught off guard and injected with large amount of Gastrea virus. This lowered her lifespan to a month and paralyzed her body. Not wanting to be a burden to everyone she left and killed herself under a tree.
- Go Out with a Smile: She has a smile on her face after she dies.
- Heroic Sacrifice: Shoma mentions to Rentaro in episode 12 that she risked her life attempting to save an Initiator she didn't know, and was injected with a lot of the Gastrea virus as a result. She then kills herself to avoid being a burden to Rentaro and Shoma, since she was bedridden and likely not to survive much longer anyway.
- Nice Girl: Midori happens to be a very kind girl at heart.
- Nice Hat: Wears a witch's hat, used to hide her cat ears.
- Shrinking Violet: She is very shy and meek and doesn't speak too loudly around others.
- Too Good for This Sinful Earth: Like Kayo, the fact that she happens to be a good person at heart makes her death tearjerking.
- We Hardly Knew Ye: Suffers this fate similarly to Kayo. She's introduced and given some brief characterization, then suffers a debilitating attack by the Gastrea which cripples her body and greatly shortens her lifespan as a result. She then kills herself to avoid being a burden to Rentaro and Shoma since she was unable to fight or move around much.
- Wolverine Claws: From her fingernails to be exact.
Voiced by: Yoshimasa Hosoya (Japanese), Adam Gibbs (English)President of Civil Security. Joins Rentaro's Group during the Third Kanto War.
- Awesome, but Impractical: His chainsaw gloves.
- Brother–Sister Team: He fights alongside Yuzuki.
- Cool Big Sis: A gender-flipped example. He's not only a cool big brother to Yuzuki, but once he joins the Gastrea-exterminating team, he gives off this vibe to everyone during his nice moments.
- Crazy Jealous Guy: Towards Rentaro when he seems to be getting a little too friendly towards Kisara.
- Defeat Means Friendship: They were already friends, but he only joins Rentaro's group after he bests him in a brawl.
- Good Old Fisticuffs: Makes good use of his chainsaw gloves in combat as a result.
- Hot-Blooded: Brash and energetic to a fault, especially when he's fighting.
- Jerk with a Heart of Gold: He's initially callous and downright rude when first asked help by Rentaro. Once he joins the group, he shows himself to be a helpful, support, and generally friendly guy.
- Nice Guy: While he can be brash and abrasive at times, he's generally relatively friendly.
- Sir Swears-a-Lot: In the dub, he adds profanity into his speeches, particularly the F-bombs.
- Adorably Precocious Child: She's fond of calling Rentaro a pervert.
- Big Brother Worship: Towards Tina, though they're not related and they're roughly the same age.
- Bratty Half-Pint: Acts this way towards Rentaro, and usually calls him a pervert.
- Brother–Sister Team: She fights alongside Tamaki.
- Clingy Jealous Girl: Acts this way towards her brother when he first sees Kisara and is smitten by her.
- Cute Bruiser: Like all Cursed Children working as Initiators.
- Defeat Means Friendship: Towards Tina after being beaten by her, but also being praised for her fighting skills.
- Genki Girl: She's more hyper than Enju, and with a tomboyish flair to boot.
- Girlish Pigtails: In spite of her tomboyish personality, she sports these. They slightly resemble a tarantula's legs, likely to hint at her being Model Spider.
- Razor Floss: Seems to employ this to trap her targets so she can attack them more easily.
- Sir Swears-a-Lot: A gender-flipped example. Like her brother, she drops a lot of F-bombs in the dub.
- Tomboy: Yuzuki has some boyish like personality traits like being brash and abrasive, likely a result of living with her older brother. There's also her abundance of swear words in the dub (and noted to be the only Cursed Child to drop a lot of profanity in her dialogue).
Voiced by: Inori Minase (Japanese)Gado's Initiator, and a participant of the Third Kanto War. Holds an IP rank of 650.
- Tsurime Eyes: Highlighting her aggressiveness.
- Undying Loyalty: Remains loyal to her Promoter Gado even after he dies, and is initially averse to the idea of becoming an IP pair with Shoma, even if only temporarily.
Kihachi SuibaraAn old friend of Rentaro, who he met during fourth grade.
- Childhood Friends: Became friends with Rentaro since fourth grade.
Hotaru KouroKihachi's Model Planarian Initiator.
Andrei LitvintsevA Belarusian Promoter and spy, and a member of the Witches Squadron. Holds an IP rank of 77.
- Doomed Hometown: His home country Belarus was completely destroyed by Libra.
Yulia KochenkovaA Belarusian Initiator, partnered with Andrei and also a member of the Witches Squadron. Holds an IP rank of 77.
Voiced by: Yuko Kaida (Japanese), Joanne Bonasso (English)The head Gastrea researcher of a medicine lab in Magata Public University Hospital who serves as a adviser and teacher to Rentaro. Eccentric, but is one of the four sages and was in charge of the "New Human Creation Plan."
- Bi the Way: Doesn't quite show the usual gay/bi cliches. In the first episode, after she jokingly referred to a corpse she did an autopsy on as her boyfriend, Rentaro answered, that he thought, that she had a thing going on with a woman named Susan.
- Black Comedy: Shown to have a rather dark sense of humor, once ironically questioning Rentaro why he has yet to commit suicide.
- Bunny-Ears Lawyer: Despite her eccentricity and sometimes act a bit immature in front of Rentaro, she's actually quite smart and is one of the four sages.
- Cool Big Sis: Serves this role to Rentaro.
- Cordon Bleugh Chef: Her cooking and sense of taste are very odd.
- Eccentric Mentor: Very much so; she loves to tease Rentaro at times.
- The Gadfly: She likes to tease Rentaro from time to time, because of how Oblivious to Love he seems at times.
- Hikikomori: She's rarely seen outside of her own laboratory.
- Mad Scientist: In spite of her eccentricities, she shows to be a valuable asset to Rentaro.
- Ms. Exposition: She provides a lot of the explanations for how things work in the series, such as when explaining to Rentaro about the procedures he underwent as a young child to enhance and fix up his broken body.
- Shipper on Deck: Supports Rentaro and Kisara getting together.
- Woman Child: Is an adult, but she sometimes acts less mature than Rentaro, unless she gets serious.
Voiced by: Kosuke Toriumi (Japanese)One of the four sages who was part of the Mechanized Soldier Plan American Division, "NEXT." He breached the agreement between the four sages and used healthy Cursed Children to create mechanized Initiators, "HYBRID." He sent Tina Sprout to assassinate Seitenshi.
- Arc Villain: One of the main antagonists of volume 2, where he orders his Initiator Tina to assassinate Seitenshi.
- The Ghost: Downplayed; he is only known through phone calls he makes with Tina.
- He Who Must Not Be Seen: He's one of the Four Sages, although never appears on screen and is only known through phone calls he makes with Tina.
- Jerkass: He virtually does not care about Tina's safety and well-being and tells her that if she fails to kill Seitenshi a final time, to kill herself.
- The Man Behind the Man: Since he doesn't appear physically, and only interacts via phone calls, he's the one behind Tina Sprout's actions.
- Meaningful Name: He shares the same name with a libertarian philosopher, Ayn Rand, who was well-known as the mother of Objectivism. Objectivism is known to have similar philosophical tenents of Existentialism, except Objectivism rejects subjectivism (which is one of the important tenets and themes of existentialism) and rejects the notion of "happiness for the greater good" as a purpose of life. This series is known to have strong existentialist philosophical themes and Rentaro happens to be a utilitarian.
- What Happened to the Mouse?: It's unknown what becomes of him after the events of Volume 2.
Arthur ZanuckOne of the four sages. Heads the Australian Division of the Mechanized Soldier Plan, "Obelisk".
Albrecht GrünewaldOne of the four sages. Heads the German Division of the Mechanized Soldier Plan.
- The Leader: Was responsible for assembling the Four Sages, and serves as their leader.
The current ruler of Tokyo Area. She fights for equal rights for the Cursed Children.
- Actual Pacifist: She's a strong believer of pacifism and believes everyone can live together in harmony, both normal humans and Cursed Children alike.
- Badass Pacifist: Despite her dedication to pacifism, she placed herself in dangerous situations during volume 2 and manages to escape house arrest placed by Kikunojou Tendo during volume 7 with the political fallout in the meeting with the city-states of Japan. Regardless, she looks badass and pacifistic at the same time.
- Big Good: A Reasonable Authority Figure who works to improve the Cursed Children's lot in life, knowing that many people refuse to accept them because of the Gastrea breakout. She also tries to perform her duties knowing that someone would attempt to assassinate her.
- A Child Shall Lead Them: She's the leader of Tokyo, and it's really hard to believe that.
- Flower in Her Hair: Her hat has a white flower attached to it.
- Foil: To her aide and advisor Kikunojou. Seitenshi is a Wide-Eyed Idealist pacifist who want to grant civil rights to the Cursed Children and be part of Tokyo's society. Kikunojou is a cynic who lived through the war and has strong hatred towards the Cursed Children; he sees the Cursed Children as vermin that need to be eradicated from society.
- Idiot Ball: Rentaro believes she's exposing herself too much when an assassin tries to take her out in episodes 5 and 6. For her part, Seitenshi says she has to maintain a public presence, though she at least does let him do things to try to ensure her survival, such as switching her out of the limo in episode 6 into one of the other vehicles in her convoy.
- Japanese Politeness: Uses very formal language at all times, highlighting her position as the Tokyo Area's ruler.
- Keigo: Speaks in very formal linguistics (highlighting her authority as ruler of the Tokyo Area), and also uses the very formal first-person pronoun "watakushi" in the Japanese version when referring to herself.
- The Leader: She's ruler of the Tokyo Area.
- Nice Girl: Really, this woman wants to implement civil rights for the Cursed Children in Tokyo.
- Nice Hat: Wears a white wide brim hat with a white flower attached to it.
- Pimped-Out Dress: She certainly stands out compared to many of the other characters due to her clothing.
- Reasonable Authority Figure: She gives Rentaro a surprising amount of freedom when he's assigned to her as a bodyguard. She also gives him the "power" he wants when he says he wants to be strong enough to protect his friends and loved ones, in the form of a Field Promotion. Also, she wants to push for civil rights for the Cursed Children and pardoned Tina, noting that Tina isn't an evil person at heart.
- Wide-Eyed Idealist: She believes that the Cursed Children can live in harmony and peace with the normal humans in society and the key to defeating the Gastrea.
- Wise Beyond Her Years: Justified, considering she IS the ruler of Tokyo after all.
- Woman in White: Wears a white wide brim hat, white dress, and has white hair.
- Yamato Nadeshiko: Serves as a motherly figure to many of the protagonists.
- Younger Than They Look: Believe or not, she happens to be roughly about Rentaro's age. Yet, the way she dresses, her mature personality, and her motherly like figure to many of the characters makes others mistake her as an adult. This trope is lampshaded by Rentaro himself.
Voiced by: Tamio Ohki (Japanese), John Swasey (English)The grandfather of Kisara Tendo and foster father of Rentaro Sataomi. He works as an advisor and aide to Seitenshi.
- Abusive Parents: He killed Kisara's parents. No wonder she hates him for it.
- Adaptational Villainy: Some of Kikunojou's more positive aspects of his character (such as his loyalty to Seitenshi, father-like relationship with Rentaro, and his sense of duty to protect the people of Tokyo) are highlighted in the light novel while still portraying him as an Anti-Villain. The anime only highlights his more evil side of his character and make him more like a Corrupt Politician.
- Anti-Villain: His hatred towards the Cursed Children is partially because of his tragic past of losing his wife, but he feels that the Cursed Children needs to be suppressed or eradicated as means of protecting humanity; and such hatred is necessary as means of defeating the Gastrea. That being said, he is strongly loyal to Seitenshi to the point to having plans to evacuate her and the citizens of Tokyo should Rentaro fail to stop the Hiruko pair (which he ironically hired by himself) or if Rentaro fails to stop the Stage V Gastrea. Having the political power and influence in Tokyo, he probably would be the guy who is willing to start a genocide on the Cursed Children, but as long as Seitenshi is alive, he probably wouldn't pull something off like that. Rentaro describes him as a very contradicting character. The anime, however, cut out a lot of his characterization and portray him to be more like a Corrupt Politician.
- Badass Grandpa: He's an old guy who lead the Japanese troops during the Gastrea War.
- The Cynic: Because he lost his wife to the Gastrea 10 years ago, he isn't really happy about Seitenshi implementing civil rights for the Cursed Children.
- Cynical Mentor: He serves as a fatherly teacher and mentor figure to Rentaro and gave some encouraging words to Rentaro, such as "If you don't want to die, live". On the other hand, he's a very jaded old man who has a strong hatred towards the Cursed Children and will do any necessary means to defeat the Gastrea, including genocide on the Cursed Children.
- Evil Mentor: Was responsible for hiring the Hiruko pair to cause chaos in the Tokyo Area.
- Evil Old Folks: He hired the Hiruko pair to stir chaos around the Tokyo Area as means of discrediting Seitenshi's implementation of civil rights for the Cursed Children (as Kohina Hiruko is a Cursed Child herself).
- Foil: To Seitenshi. While Seitenshi is a Wide-Eyed Idealist pacifistic ruler of Tokyo who wants to implement civil rights for the Cursed Children, Kikunojou is a cynical old man who survived through the war and will do anything to prevent granting the Cursed Children civil rights to the point of hiring the Hiruko pair to create a 0% Approval Rating for the Cursed Children.
- Freudian Excuse: His hatred towards the Cursed Children is somewhat justifiable when his wife was killed by the Gastrea 10 years ago and the eventual fate of many of the Cursed Children. That doesn't really justify his action of hiring the Hiruko pair to cause trouble in Tokyo though.
- Irony: Despite his strong hatred towards the Cursed Children, he actually strongly distrusts Sogen Saitake, the Osaka Area's ruler.
- Jerkass: Not only does this guy want complete genocide on the Cursed Children, he also hired the Hiruko pair to stir chaos around Tokyo.
- Karma Houdini: Given that the anime adapted the first four volumes, he gets off scot-free for the stuff he was responsible for, such as hiring the Hiruko's to discredit Seitenshi's plans to pass some laws to give the Cursed Children a better chance at life.
- The Man Behind the Man: He's the one responsible for letting the Hiruko pair go on a chaotic rampage and releasing a Stage V Gastrea in the Tokyo area.
- Necessarily Evil: He feels that the hatred of the Cursed Children and suppression of their rights is necessary to defeat the Gastrea. This involves hiring the Hiruko pair as well.
- Power Of Hate: His hatred towards the Cursed Children allows him to hold a lot of political influence and power in Tokyo, thus making Seitenshi's goals of implementing civil rights on Cursed Children difficult.
- Undying Loyalty: Subverted. His vehement loyalty to Seitenshi is a farce, in that he's willing to do evil things as means of discrediting Seitenshi's goals of implementing equal rights for the Cursed Children.
Miori ShibaStudent Council President at Rentaro's school, and the daughter of the president of the company that sponsors Rentaro and provides him and Enju with equipment to fight the Gastrea with in exchange for the publicity when they use said items.
- Action Girl: She knows how to fight just like Kisara, though their Cat Fight in episode 5 isn't seen directly. Instead the outside of Rentaro's apartment is shown, along with some bulletholes. Later the lights go out and Rentaro laments that he won't get his security deposit back now due to the damage the two girls caused.
- Clingy Jealous Girl: She butts heads with Kisara regarding Rentaro, since both of them like him, and hate each other as a result of it. Hilariously, when Kisara draws her blade at Miori, both Rentaro and Enju don't stop them. Rather, they just pick up the table with all the food and move it out of the living room so the two girls can duke it out.
- Combat Hand Fan: The fan she carries around is also used for combative purposes.
- Kansai Regional Accent: Speaks with this accent.
- Kimono Is Traditional: Always wears a kimono no matter how impractical it is in combat.
- Mission Control: She does this for Rentaro and the others fighting against the Gastrea in episode 12 and 13.
- Screw the Rules, I Have Money!: When Rentaro needs weapons, she's more than happy to provide him with them. Of course she often does it with the intention of luring him over to her and away from Kisara, which frustrates the latter to no ends.
- Smarter Than You Look: She appears to be The Ditz at first, but she's actually quite smart, and certainly knows how to press Kisara's Berserk Button when it comes to Rentaro.
- Student Council President: At Magata High School, where Rentaro attends when he's not fighting Gastrea.
- The Tease: She enjoys doing this to Rentaro, especially if Kisara is around to watch it.
- Ax-Crazy: He develops this look in episode 7 after shooting Tina.
- Green-Eyed Monster: He's rather angry that Rentaro was offered a bodyguard job by Seitenshi in episode 5. While Rentaro was debating whether to take the job, Takuto threatens him not to, which then causes the former to accept it after all.
- Fingore: His finger is shot off by an angry Rentaro after Seitenshi gives him a Field Promotion, allowing the latter to outrank him.
- Four Eyes, Zero Soul: He at first seems to be a reasonable person, greeting Rentaro normally when they first meet. However, shortly after this, he shows the other side of his personality, and is quite the jerk about Rentaro even being offered the mission in the first place.
- Jerkass: He was a jerk to Rentaro. Heck, he shot Tina as well.
- Laser-Guided Karma: Due to the terrible treatment he gives Rentaro and Tina, it's not likely anyone would object to the way Rentaro pays him back in episode 7.
- The Mole: Rentaro suspects he was one in episode 7, after Takuto tells him they came up with a route to take Seitenshi to her latest meeting to avoid ambush spots like before. Tina later calls Rentaro to let him know that said route she got from her master seems oddly strange in that there's one spot she could easily fire at Seitenshi from. Tina later gets shot by Takuto, who then mentions that Seitenshi was taken to the meeting without incident, and seemed to know where she and Rentaro were at. In the end though Rentaro wasn't able to fit enough pieces of the puzzle together to determine this.
- Scary Teeth: He displays some in episode 7 to go with his Ax-Crazy look.
- Why Don't Ya Just Shoot Him?: Averted, he does shoot Tina after Rentaro stops her in episode 7. He then wonders how many lead bullets it would take to kill her since he didn't have any varanium bullets on him.
- Would Hurt a Child: Attempted to kill Tina even though he knows that normal bullets are ineffective against Cursed Children.
Voiced by: Kazuyuki Okitsu (Japanese), Houston Hayes (English)One of Kisara's older brothers and a politician.
- Ambition Is Evil: He embezzled the Monolith construction money so that he can hold a political position in Tokyo.
- An Arm and a Leg: Kisara sliced off both of his legs with one of her attacks.
- Asshole Victim: He deserved to be killed, seeing that he not only killed Kisara's parents but also endangered millions of lives.
- Blade on a Stick: Uses this as a weapon during the duel between Kisara.
- Corrupt Politician: Easily fits into this description. He was responsible for the death of his and Kisara's parents. And later he embezzled money by using substandard materials to create the Monolith that collapsed with and pocketing the money in hopes of getting enough money to buy influence and get elected. Kisara puts a stop to that when she kills him.
- Four Eyes, Zero Soul: He has glasses and is an evil individual all around.
- It's All About Me: Doesn't care what happens to anyone, so long as he can get a lot of money, and get elected as a politician. Kisara puts an end to that when she kills him for his actions.
- Jerkass: He's not only responsible for Kisara's parents' deaths, he also placed millions of lives at risk for his personal selfish gains.
- Karmic Death: Kisara kills him, though Rentaro fears she may be going down a slippery slope.
- Self-Made Orphan: Was one of the individuals responsible for the deaths of his and Kisara's parents.
- Sleazy Politician: Embezzled the Monolith construction money so he could buy his way into a political position.
- Walking Spoiler: The spoiler markers should be a good indication of what happens to him.
- We Hardly Knew Ye: Hardly anything about him is known across from the fact that he's a Corrupt Politician prick who gets his comeuppance at Kisara's hands.
- You Killed My Father: The dick was responsible for the death of his and Kisara's parents.
Voiced by: Takashi Matsuyama (Japanese)
Voiced by: Tomomichi Nishimura (Japanese), Chris Ayres (English)An elderly man who cares for the Cursed Children in the Outer Area of Tokyo.
- Cool Old Guy: He looks after the Cursed Children in the Outer Area of Tokyo, and teaches them to better control their emotions so their red eyes won't show.
Voiced by: Unshou Ishizuka (Japanese), Ty Mahany (English)Ruler of the Osaka Area. He aspires to rule the world someday.
- Ambition Is Evil: He seeks to reunite Japan under his fist, then uses his power to take over the world. In the Fugitive Arch, he's involved with a Right-Wing Militia Fanatic organization that shares his goals and they were experimenting on Gastrea for world domination.
- Frame-Up: He framed Rentaro to advance his goals for world domination.
- Godwin's Law: Only in the light novels. To be more precise, Rentaro compares him to Adolf Hitler on how they both take advantages of tragedies and wars, reunite the people, and use the advantage as a means of establishing a military superpower to Take Over the World. Also help to note that he is part of a Right-Wing Militia Fanatic organization, as revealed at the end of the Fugitive Arc.
- The Leader: The ruler of the Osaka Area.
- The Man Behind the Man: In the Fugitive Arc, he was involved in framing Rentaro for murder to advance his world domination goals and was working with a Right-Wing Militia Fanatic organization.
- Take Over the World: This is his goal.
In GeneralTropes applying to the Gastrea species as a whole.
- Achilles' Heel: Varanium. It completely nullifies their Healing Factor and it is said that if a Gastrea was put into a room made of Varanium, it'll die a slow and painful death. If not for this metal, humanity would've been wiped off the planet. Though the exact scientific details as to why they're weak to Varanium has yet to be explained.
- Always Chaotic Evil: The Gastrea are portrayed as a race of monsters that will always target humanity no matter the circumstances, and seem to be dead set on wiping them off the planet for unknown reasons that go beyond normal animal instincts.
- Big Bad: The main antagonists of Black Bullet. They were responsible for the decline of humanity, and Rentaro must work to prevent them from destroying the Tokyo Area and the world.
- Eldritch Abomination: Stage IV and V Gastrea appear as hideous and massive monstrosities.
- Healing Factor: The Gastrea can heal their wounds very fast, making them nearly impossible to kill by conventional means. It's because of this reason that humanity nearly went extinct, and only Varanium is capable of completely nullifying their healing factor.
- It Can Think: According to Sumire, there's a theory that the Gastrea are actually highly intelligent which would explain their unnatural behavior towards humans.
- Mix-and-Match Critters: Some Gastrea can be hybrids of various animal traits. The Gastrea that appeared in the prologue of the first volume was said to look like a dinosaur with modern bird wings and insect compound eyes.
- Stellar Name: Stage IV Gastrea are named after stars (like Aldebaran) and Stage V Gastrea are named after Constellations.
- Ultimate Lifeform: Considering that they managed to become the top of the food chain in not even a year since they appeared, many scientists consider them as such as they now make up Earth's ecosystem.
- The Virus: The Gastrea Virus can heavily alter human DNA and mutate the hosts into monsters very quickly, bypassing millions of years of evolution in just a couple of minutes.
- Was Once a Man: Every single Gastrea monster was once a human that got infected at some point, or a Cursed Child whose body became completely corroded by the virus.
AldebaranThe Stage V Gastrea that attacked Tokyo area during the Third Kanto War. It was the former right hand to the Stage V Taurus before Taurus was killed.
- Arc Villain: The main antagonist of the Third Kanto War Arc.
- The Dragon: Served as the right hand to Taurus before the latter's downfall at the hands of the unknown IP 1 pair.
- The Dreaded: Due to being extremely hard to kill, it earns this reputation when people hear that it's approaching.
- Healing Factor: Aldebaran has one of the strongest healing ability shown in the series, as long as its body is not completely destroyed, it can come back to life no matter what damage it sustained.
- Point Defenseless: It launches some spikes out of its back at Rentaro as he closes in on it. Like the trope implies, they aren't very effective against him.
- Superpower Lottery: It is hard to kill, it can release pheromones to control an army of Gastrea, it can corrode Varanium and it is larger and stronger than most Stage IV Gastrea. This is why it's The Dreaded when it shows up after the Monolith breach.
- Knight of Cerebus: Just when you are wondering why humans are so afraid of Gastrea, this thing shows up and explains it in action and drag the tone of the novel further in to darkness.
ScorpioThe Stage V Gastrea that appeared in volume 1.
- We Hardly Knew Ye: It appeared only briefly before getting killed by the ladder to heaven.
TaurusOne of the Stage V Gastrea and leader of the famous Taurus army. It and its army destroyed many cities in the Middle East and Africa, but was eventually defeated by the IP 1 pair. After its death its army scattered, ending the threat of Taurus.
- The Dreaded: Before it was taken down by the IP 1 pair, any city that it and its armies' paths were on was destroyed. No survivor was ever found.
- We Hardly Knew Ye: Was killed before the start of the series by the IP 1 pair.
SagittariusOne of the Stage V Gastrea. Mentioned in volume 7.
- Improbable Aiming Skills: During the great Gastrea war it shot down nearly all of mankind's satellites all by itself.
LibraOne of the Stage V Gastrea. Debuted in volume 7 and appeared near the Sendai area.
- Plague Master: It has the ability to create different types of air borne diseases. This troublesome ability caused large amounts of deaths during the Gastrea War.