The cast of Knights of Sidonia and associated tropes. Beware of unmarked heavy spoilers.
Voiced by: Ryota Ohsaka (JP), Johnny Yong Bosch (EN), Arturo Castañeda (credited as Arturo Castañeda Mendoza) (LA)
The protagonist of the series, Nagate was raised in isolation in the depths of Sidonia, with only his grandfather Hiroki Saito and a Guardian pilot simulator for company. Nagate discovers society once his food supply runs out and is forced to search for more. Captured by the local authorities of Sidonia, once his grandfather's identity as a famous pilot is discovered, Sidonia's government puts him on the road for elite Guardian training.
Nagate faces many hardships adapting to society and his duties as a pilot, but finds friendship and love among his peers. Eventually, he finds more comfort in his role in society, and becomes Sidonia's best pilot.
- Accidental Pervert: He has a few moments like this during the lighter segments. Usually suffers some Amusing Injuries as a result.
- Ace Pilot: Tanikaze is Sidonia's first ace in living memory, being the only one who has survived long enough to get that title.
- Ace Custom: By necessity since he was trained to pilot Type 17 guardians, and the current Type 18's have a different setup.
- All-Loving Hero: One of Nagate's reasons for being a pilot is that he loves Sidonia and its people. He even says to Kunato that even though he can't forgive him for causing Hoshijiro's death, he still wants to fight alongside him, because he's one of Sidonia's people that he loves.
- Amusing Injuries: Often receives them when En thinks he's peeping on her. Notable in that they're only amusing because he's Made of Iron, they look extremely painful and debilitating and anyone without his healing factor would be hospitalized for weeks.
- Babies Ever After: He and Tsumugi have a daughter named Nodoka.
- Big Eater: Tanikaze is seen as one, on account of being unable to photosynthesize like most of the "humans" on Sidonia. Downplayed, as he doesn't really eat any more than a normal human do. It's just the rest of the crew are genetically-engineered humans who eat very little. At one point, he even turns down a truly massive fish because "I don't eat that much."
- Bring My Brown Pants: He wets himself during his first real flight in a Guardian.
- Can't Hold His Liquor: Gets drunk and passes out after drinking from just one cup of sake.
- Cartwright Curse: His relationship with Hoshijiro ended in tragedy when she took a (metaphorical) bullet for him and ended up getting absorbed by the Gauna. And as of chapter 77 it's happened again: after chasing (and killing, finally) Ochiai within the upper atmosphere of Lem's star, which was a suicide run and he knew it, a badly injured Tsumugi saved his life at the expenses of her own by diving in after him and using her body to protect him from the heat.
- Chick Magnet: A considerable part of the female cast is attracted to him. He is later voted the third most popular man on board the Mizuki (among women) even after being accused of being a peeping tom.
- Clones Are People, Too: He was created to be a Body Backup Drive for Hiroki Saito, who objected, stole his clone as a baby, and raised him as his grandson.
- Crouching Moron, Hidden Badass: Dear lord does this fit him. In the day to day life on-board the Sidonia He's a comical Fish out of Water; awkward, gullible, few social skills (most of which are outdated), no understanding of women, routinely embarrasses himself, etc, etc. He's also THE best pilot in the Ship's crew; give him a Guardian with a Type 17 control scheme and watch him fly circles around the other pilots. He quickly racks up the highest kill count in the story.
- Fish out of Water: He's only known about life through his grandfather. So when he joins the rest of Sidonian society, he's unaware of many things, such as Izana's hermaphrodite status, or that other people have been genetically modified to have some photosynthesis abilities to reduce their need for food.
- Good Thing You Can Heal: Nagate gets injured a lot, but this is mostly played for laughs because of his Healing Factor.
- Graceful in Their Element: Nagate does poorly in a Type 18 simulator. But when he's put on board a Type 17, he flies and fights in it as if he were wearing a glove.
- Groin Attack: When his suit inserts its catheter for the first time, Tanikaze screams in pain.
- Healing Factor: As a result of being an immortal enhanced clone, he rapidly recovers from injuries that would incapacitate or kill others. He's also in a cast at first, due to injuries he got trying to avoid the polie. He later he says he felt okay but he was forbidden from removing it, probably so as not to arouse suspicion of this trope.
- The Hero: Of Sidonia, just like Hiroki Saito once was. People who once distrusted and even attacked him at the beginning of the series come to respect and idolize him.
- Iron Butt Monkey: He endures all sorts of abuse, which he rapidly recovers from due to his healing factor.
- Identical Grandson: Due to being a clone, he is identical to his "grandfather".
- Idiot Hair: He has an ahoge poking out of his messy hair, though it's kinda hard to spot at times.
- Instant Expert: Subverted. He seems to be a natural at piloting and fighting in a guardian, but only because he was taught by his grandfather, who also had him do countless hours training in the simulators. And even then he was only really comfortable in the Type 17, not the newer Type 18 design.
- Interspecies Romance: He eventually confesses his feelings for Tsumugi, who is half Gauna and 15 meters taller than him.
- It Sucks to Be the Chosen One: When one of the Honoka sisters bemoans Nagate for always receiving the best gear, he states that while he does in fact get all the neat upgrades and experimental gear, it's also his responsibility to fight things like the Crimson Hawk Moth - a Gauna that has repeatedly over the series killed multiple pilots without effort - by himself.
- Made of Iron: His healing factor also allows him to shrug off stuff that would normally incapacitate or even kill your average person. He once took a shock dart to the back of the neck without any effect, and had to be shot three more times in the facenote before he finally went under.
- The Mourning After: He spends almost every moment of his spare time with the Hoshijiro Ena until she's taken by Ochiai, and Kobayashi and Yuhata directly order him to forget about her. He immediately complies and seemingly forgets about her until Tsumugi is born.
- New Transfer Student: When he is first discovered and apprehended, instead of punishment he is instead immediately enrolled in the academy. However, he is looked down upon by many of the others, because somehow he managed to become a cadet, whereas everyone else has to work hard to get selected, and is usually celebrated within the community when they become cadets.
- No Social Skills: Not only is Nagate awkward due to living his whole life with only one man for company, what few social skills he does have appear to outdated and old-fashioned.
- Normally, I Would Be Dead Now: His healing factor is rather potent. In an early chapter, he went into cardiac arrest after a nasty hit, but after a few seconds his heart rhythm restarted on it's own (which should be impossible) and he jumped back into the fight like nothing had happened.
- Oblivious to Love: As a result of his lack of social skills, Nagate is rather dense. He manages to realize that Hoshijiro reciprocates his feelings for her, but that's about it; all other characters who like him are out of luck.
- Promotion to Parent: Adopts Ichigaya Teruru after she is abandoned by the remnants of the pacifist movement.
- Raised by Grandparents: Raised by his grandfather Hiroki Saito until he died three years ago. The truth is that Nagate is his clone and Hiroki considered him his child.
- Taught by Experience: Part of the reason the government values Tanikaze so much is because of his huge aptitude for piloting Guardians. And the reason for that seems to be because he had literally nothing to do but log hours into a Guardian simulator and take lessons from his only companion/parent, a former pilot himself. The other part is that said "parent" was an incredibly renowned war hero.
- Trademark Favorite Food: While he's willing to try just about any kind of food, his love of onigiri stands out. Most of the time he's seen eating (or humorously failing to eat) something, it'll be a riceball.
- Tyke-Bomb: Was raised from birth by Sidonia's former Ace to become the next one.
- Walking Transplant: He was created to serve as the new immortal body for Hiroki Saito. Fortunately, Hiroki saved Nagate from this fate by kidnapping him.
Voiced by: Aya Suzaki (JP), Stephanie Sheh (EN), Andrea Orozco (LA)
The second-ranked trainee in Nagate's class at the start of the series, Hoshijiro is Nagate's main Love Interest, being the first woman he ever saw and felt romantic affection for. Following the battle with the Gauna mimicking Yamano Eiko and being rescued by Nagate, she reciprocates his feelings.
This turns out to be a rather brief relationship, as in their next mission Hoshijiro is killed saving Nagate and assimilated by a Gauna, her memories and DNA used for creating a trio of powerful Guardian-type Gauna. Gauna 489 and 491 are killed in their first sortie, but Gauna 490 - implied to be the same Gauna that assimilated Shizuka - escapes and becomes a reoccurring antagonist, codenamed "Crimson Hawk Moth". An Ena sample of Gauna 491 shaped like Hoshijiro is retrieved by Nagate, and is eventually used by Ochiai to give birth to Tsumugi and later Kanata. However, a second Ena sample was retrieved from Gauna 490, and was later implanted with Tsumugi's consciousness.
- And Then John Was a Zombie: She's assimilated early in the manga and several copies of her show up as powerful antagonists, most notably the Crimson Hawk Moth.
- Body Horror: Hoshijiro finds out first hand what Gauna do to their victims, and they use a corrupted parody of her body as a Ena for the Crimson Hawk Moth.
- First Girl Wins: She's the first girl Nagate sees, and she and Nagate fall in love with one another. Even after her death, she ends up having much relevance in the series, as Nagate is shown to still miss her even dozens of chapters after her death, and her copies appear to retain some degree of affection towards him.
- Heroic Sacrifice: Shizuka is assimilated while knocking a shell-shocked Nagate out of the way of a Gauna.
- Luminescent Blush: When she was forced to filter her urine to give a dehydrated Nagate water to drink, and following that every other romantic moment they had together leading up to her death.
- Rescue Romance: Her relationship with Nagate begins with him rescuing her after she ejects from her Guardian, and their subsequent rescue by Sidonia's defense team.
- Sci-Fi Bob Haircut: Her hairstyle, to go with the futuristic setting.
Voiced by: Aki Toyosaki (JP), Melissa Fahn (credited as Joie Marlowe) (EN), Gisella Ramírez (LA)
One of Nagate's fellow pilot trainees at the series' beginning and a person of the third gender. One of the first people to befriend Nagate and treat him as a fellow human being, Izana proves to be his closest friend as the series progresses, and a source of great moral support. Izana quickly develops feelings for Nagate, which go mostly unnoticed due to his lack of social awareness.
Izana eventually becomes a regular pilot and loses an arm and a leg at the hands of the Crimson Hawk Moth, but obtains mechanical limbs to compensate.
- Ambiguous Gender: Initially Nagate couldn't tell if Izana was a boy or a girl, and when they noticed him staring they informed him that they're technically neither. They later become definitively female.
- An Arm and a Leg: On Izana's first mission as a regular pilot, their right arm and left leg are destroyed by the Crimson Hawk Moth. The anime changes this to losing those same limbs during the battle against the Large Union Cluster, when Tsumugi shielded Sidonia from the giant Higgs particle cannon (as Izana's first battle in the anime happened rather differently).
- Artificial Limbs: Izana's artificial right arm, which doubles as a Badass Transplant and Swiss Army Appendage. It grants them enhanced strength, fingers which can split and extend and a BrainComputer Interface.
- Buxom Is Better: Izana becomes quite curvy after turning female, much to Yuhata's amazement and annoyance.
- Clingy Jealous Girl: Gets quite upset when Nagate seems to be getting a little too friendly with Shizuka, and later with any other girl.
- Cowardly Lion: At the beginning of their pilot career.
- Custom Uniform of Sexy: Izana gets a very distinct skintight, half-black pilot suit.
- Cute Clumsy Girl: A trait Izana inherited from their grandmother.
- Cyborg Helmsman: Of an old, armed Sidonian cargo ship during the Teruru rescue mission, using their robotic arm to interface with it.
- Does Not Know His Own Strength: Nagate is comically injured several times because Izana was not used to the superhuman strength of their new right arm.
- Even the Girls Want Her: Wins the "most popular among both men and women" category in the Mizuki crew's popularity contest.
- Everybody Wants the Hermaphrodite:
- Heartbreakingly averted, at least at first. Izana loves Tanikaze deeply but he only likes women (and is incredibly dense, to boot). However, Izana eventually transforms into a female. This is because Third-Genders like Izana aren't really "Hermaphrodites" per say; they're humans who don't have a set gender, but have the ability to become male or female later in life. The transformation is triggered when, consciously or not, they decide on a mate, and Izana's began after she fell in love with Nagate.
- Izana is later voted the most popular person on board the Mizuki among both men and women. By that point in time Izana has fully become a woman, however, making this a subversion of sorts.
- Gender Bender: Third-Genders like Izana start off agender, but will become either male or female after choosing a mate. Hence, they start turning female after developing feelings for Nagate.
- Hermaphrodite: The series' first and most focused on example.
- Identical Grandson: Yure remarks that after their transformation Izana looks like her when she was young.
- The Lancer: Becomes one in the course of the story to Nagate's Hero.
- Locked Out of the Loop: Izana's grandmother keeps them in the dark about her real work and true standing in Sidonia. It lasts till chapter 65.
- Nice Guy: It's established in their first appearance that they got a very calm and sweet disposition. However...
- Official Couple: Izana hooks up with Yuhata at some point during the 10 year timeskip in the final chapter.
- O.O.C. Is Serious Business: They becomes a little temperamental in later chapters, prone to pouting and and very Tsundere-ish outbursts. It's a hint that Izana's body is undergoing stressful changes.
- Raised by Grandparents: Raised by their grandmother Yure Shinatose.
- Sensory Overload: They have to keep their eyes closed when they processes data from sensors in order to prevent an overload.
- Slow Transformation: Izana's gradual transformation into a female takes more than thirty-three chapters. It also embarrasses the hell out of them.
- Super Senses: They can receive and process data from Sidonian sensors via their BrainComputer Interface. Their sensor radius amplification device amplifies it with help of the other Guardians and drones to the point that they surpass the senses of chimeras, the most advanced individuals of the setting.
- Unsettling Gender Reveal: Unsettling for Nagate, who accidentally copped a feel Shinji-style when he tried to catch Izana after they trip. Yuhata is also shocked when she sees Izana has breasts bigger than hers.
- Wardrobe Malfunction: How their gender change was finally confirmed. Their pilot suit would no longer recognize them thanks to too many "adjustments", so they tried hacking into it to force it to accept them. It lead to a malfunction which caused the suit to rip itself to shreds... in the middle of a zero-g hallway... right in front of Nagate (who promptly slams head-first into a doorway).
- Wetware CPU: Izana's brain is used to process data from various Sidonian sensors into visual and auditory output.
Voiced by: Takahiro Sakurai (JP), Todd Haberkorn (EN), Emmanuel Bernal (LA)
The highest-ranked trainee in Nagate's class and heir to Kunato Industries, the company developing the Type 18 Guardians that compose most of Sidonia's main force at the start of the series. An arrogant and vain man with little respect for his peers, Kunato develops a rivalry with Nagate due to him being assigned the Tsugumori, who he viewed as rightfully his. He sees Nagate as a thief of his glory and takes every opportunity he can to hurt or embarrass him. This culminates in him sabotaging a mission that results in Hoshijiro's death and assimilation by Gauna.
After retiring from being a pilot to focus on his father's company, Kunato undergoes emotional turmoil when he realizes that Nagate still accepts him, even if he can't forgive him for causing Hoshijiro's death. While trying to make amends and find technology that could help Sidonia, his body is secretly hijacked by the mind of Ochiai.
- Ambition Is Evil: Just listen to him talking to himself about what Nagate took from him.
- Artistic License Military: Combined with Artistic License Law. Kunato was able to pin the blame for the deaths caused by his sabotage on Nagate apparently due to no one bothering to check the flight recorders from any of the Gardes in his squad, which should have easily shown that he switched over to a private transmission to Nagate. This is explained in the anime as having the flight logs and combat data being highly classified for some reason. Kunato got away with the sabotage because nobody could have publicly come to Nagate's defense.
- The Atoner: After seeing the Crimson Hawk Moth in action, he sets out to redeem himself for his past misdeeds.
- Break the Haughty: Norio suffers a great deal because of his arrogance, and becomes a better person because of it.
- Catapult Nightmare: In the anime he wakes up screaming after having a dream about the Crimson Hawk Moth exacting revenge on him.
- Character Development: Despite spending a good portion of the series as Ochiai's Meat Puppet, Kunato resolves to redeem himself and become a better person in the final arc, and succeeds.
- Engineered Heroics: Kunato sabotages a mission in a way that makes Tanikaze look at fault. As mentioned, doing so also ends up getting Hoshijiro killed.
- Establishing Character Moment: In the anime, it's not long after he's introduced that he deliberately strikes Hoshijiro, for no reason and without a word, then breaks Nagate's arm when the latter comes to her defense, again saying nothing, and he goes unpunished despite numerous witnesses.
- Expository Hairstyle Change: In the Distant Finale he's cut his hair short, symbolizing his newfound maturity.
- Green-Eyed Monster: He's intensely jealous of Nagate for getting to pilot the Tsugumori and eventually becoming more famous than him. This jealousy results in Hoshijiro's demise, the rise of the Crimson Hawk Moth, and eventually allowing Ochiai's mind to take his body.
- Grand Theft Me: He was been completely taken over by Ochiai's original evil persona until it transfers to Kanata.
- HeelFace Door-Slam: Kunato's attempts to redeem himself backfire when he enters one of Ochiai's hidden labs and is taken over by him. After being freed he becomes a far better person than he was before.
- It's All About Me: Kunato was extremely arrogant and entitled, believing that only he had the right to pilot the Tsugumori.
- Jerkass: Quite a lot, and just as he starts to undergo Character Development, he's hijacked by Ochiai and becomes even worse.
- Karma Houdini Warranty: Was established as a major jerkass, and did many nasty things without consequence, finally culminating in sabotaging Nagate during an especially dangerous and delicate mission against the Gauna. When the Crimson Hawk Moth shows up, he begins to not only realize that he was wrong, but that he actually feels sorry for it, and tries to atone. Nothing goes right for him, and he only succeeds in making things worse for everyone, including himself.
- Meaningful Name: Both Nori and Mozuku are types of seaweeds.
- My God, What Have I Done?: Seeing the Crimson Hawk Moth in action sends him into a Villainous BSoD in the anime, and after Nagate tells Kunato that he still wants to fight alongside him as a pilot even though he can't forgive him for causing Hoshijiro's death, Kunato is moved to tears. The chapter this happens in is even named "Kunato Norio's Emotional Turmoil". After being freed from Ochiai's control, he seeks to redeem himself.
- Netorare: Kunato's relationship to Hoshijiro and Nagate has shades of this, particularly after Ochiai takes over and creates Tsumugi out of the Hoshijiro Ena.
- Nice Job Breaking It, Hero!: His sabotage of a mission to discredit Nagate was not only petty, but put En in a coma and - far worse - resulted in Hoshijiro being assimilated into the Gauna and becoming the Crimson Hawk Moth. It also lead to the deaths of multiple other pilots due to the Gauna's tail they were suppose to sever still being attached and able to attack.
- Odd Friendship: Kunato befriends Toutarou Yamano, the younger brother of Eiko Yamano. What makes this odd is the notion of the once-haughty and arrogant Kunato having friends at all, though it shows the Character Development he has undergone.
- Screw the Rules, I Have Connections!: Gets away with neglecting his duties as trainee representative and injuring fellow trainees thanks to the influence of his family.
- Would Hit a Girl: He hits Izana rather hard during the festival after she accidentally bumps into him.
Voiced by: Ayane Sakura (JP), Erin Fitzgerald (EN), Andrea Cedillo (LA)Norio's cloned sister and voice of conscience. She is murdered by Ochiai's doll and resurrected as his puppet.
- Artificial Human: By Word of God, Mozuku is actually a sped-up and Gender Flip-ed clone of Norio ordered by himself so he can devote his time to training. Toxine's body before her takeover of Mozuku is a miniature robot made by Ochiai.
- Back from the Dead: Yure manages to restore her body and mind in the final arc.
- Grand Theft Me: Toxine kills Mozuku and stuns Norio, implanting Ochiai's consciousness in his body. Ochiai then resurrects the former and put Toxine in control of her.
- Meaningful Name: Both Nori and Mozuku are types of seaweeds.
- Morality Pet: She functioned as Norio's voice of conscience.
- Number Two: She was this to Norio, and later The Dragon for Ochiai.
- Off with Her Head!: She's decapitated and dismembered by Toxine — Ochiai's doll — while examining some cacti.
- Only Mostly Dead: Toxine hijacks a Guardian in order to assist Kanata's breakout and is shot down by Samari. Her body survives thanks to the reinforced cockpit of the Guardian.
- Restraining Bolt: As Tsumugi's "pilot", Toxine's main purpose was to stop Tsumugi from turning on Sidonia, or more importantly Ochiai.
- The Stoic: After being resurrected she has a perpetually emotionless expression.
- Traumatic Haircut: Cut her long hair after she was resurrected as Toxine.
- The Undead: She was decapitated and dismembered, through Ochiai stitched her back up and resurrected her. She's later fully resurrected by Yure.
- Weaponized Offspring: Toxine is implied to be the rescued Ghost in the Machine of Ochiai's failed prototype Chimera.
Voiced by: Eri Kitamura (JP), Cristina Valenzuela (EN), Lizette García (LA)
A "family" of clones created for Kobayashi to form a dedicated pilot force.
- Body Horror: Shou is transformed into a Guana but completely retains her human mind and appearance - to a degree - until she realizes what she's become and starts to lose control over her new body until she's mercy-killed.
- Clones Are People, Too: They are usually treated as individuals and have their own personalities.
- Mauve Shirt: Of the Honokas who are named in manganote only the first two have survived thus far.
- Pervert Revenge Mode: En is quick to assume Nagate is trying to peep on them whenever he accidentally sees her and her sisters naked and attacks without mercy.
- Stronger Than They Look: They can kick metal doors off their hinges and jump vast heights and across rooftops.
- Theme Naming: Their names are Kanji/Chinese characters with allusions to fire.
- Tsundere: Ren and especially En can be very nice, but they have a hair-trigger temper. Ren acknowledges this and justifies it by saying that while they're all fast maturing physically and well-educated, they're still too young to be mature emotionally and have a difficult time controlling themselves because of it.
- Tyke-Bomb: They were born and raised to become Guardian pilots and fight Gauna.
- Underestimating Badassery: Angry that she had to fix the damages she cause, Ren boasted that En and her were physically superior to Lala despite Lala's strength and proclaimed that she could kick Lala's ass. Unfortunately Lala was standing right behind her and took this as a challenge. Cue the curbstomping...
- You Gotta Have Blue Hair: They have pink hair. Also counts as Curtains Match the Window.
- Younger Than They Look: The first set of sisters are just five year old, and they have a second set that is less than a year old as well.
Voiced by: Atsuko Tanaka (JP), Cindy Robinson (EN), Jocelyn Robles (LA)
- The Ace: Ranked #5 in Sidonia and probably the most competent squad leader.
- Action Girl: She's one of Sidonia's best pilots.
- Babies Ever After: She hooks up with Seii Ichirou and has several kids.
- Boobs of Steel: She's quite buxom, and one of the best pilots on the field.
- The Chains of Commanding: She blames herself for every pilot who's killed under her command and questions her worth as a squad leader.
- Do You Want to Copulate?:
- Thanks to a rumor started by Seii, the male members of her squadron believe they'll get to... photosynthesize with her if they kill enough Gauna. She vehemently turns them down every time.
- Ironically, when Nagate comforts her over her insecurities, she starts to tell him she's in the mood for a little photosynthesis... and then notices he's passed out and orders another cup of sake instead.
- Heroic BSoD: After most of her squad was killed during the asteroid mission.
- Identical Grandson: She inherited her pilot suit from her grandmother who was the pilot of a Type 16.
- Screw the Rules, I'm Doing What's Right!: She leads over 200 Guardians on an unsanctioned rescue mission to retrieve Nagate and Shizuka.
- So Beautiful, It's a Curse: All the boys on her squad kept pestering her to "photosynthesize" with them. She continually declines, though she did show interest in Nagate.
- Tomboyish Ponytail: She keeps her hair tied up in a ponytail, which emphasizes her tough personality.
- Tsundere: While she responds to the boys' advancements with scorn and violence, she cares deeply about them all.
Voiced by: Kosuke Toriumi (JP), Spike Spencer (EN), Roberto Mendiola (LA)
- Amazon Chaser: He's obviously interested in Samari.
- Bullying a Dragon: When he teases Tsumugi about Nagate - who is on a "date" with Izana - being absent, she nominates him to be her replacement partner and nearly destroys his Garde.
- Butt-Monkey: Gets beaten up by girls even more than Nagate.
- Casanova Wannabe: He hits on just about every girl he meets, especially Samari.
- Chivalrous Pervert: Gets really serious when the mission or Samari is in danger. Emphasized by the TV version during the astroid mission.
- Crouching Moron, Hidden Badass: Holds the highest kill count among Type 19 pilots.
- Did Not Get the Girl: He ultimately didn't hook up with Samari, but is still close enough friends with her that her kids call him Uncle.
- Masochism Tango: He constantly pesters Samari about "photosynthesizing" with him, only to be vehemently turned down each time.
The Sidonia's Crew
Voiced by: Sayaka Ohara (JP), Wendee Lee (EN), Carola Vázquez (LA)
The mysterious, mask-wearing captain of Sidonia. A capable and experienced leader, she leads Sidonia through its crises with determination and ruthlessness. It is later revealed that she is immortal, alongside the rest of Sidonia's council, and that she personally knew Hiroki Saito, Nagate's "grandfather", which is why she helped him become a pilot.
- Hands-Off Parenting: She's Nagate's legal guardian, but they don't have much contact with each other because of their jobs. This is partially deliberate on her part because she doesn't want a repeat of what happened between her and Saito.
- I Did What I Had to Do: She is determined to win the war against the Gauna at all costs, and makes a number of callous and ruthless decisions with this justification.
- I Just Want to Be Normal: Her hobby is... removing her mask and pretending to be a random bystander, like a nurse or an innkeeper.
- Iron Lady: She has been the captain of the Sidonia for centuries, and can be calculating and ruthless when the situation calls for it.
- Lady of War: She is normally dressed in elegant clothes - in one case even sporting a kimono - but she has been fighting the Gauna for longer than most of the Sidonia's passengers have been alive.
- Mask Power: She and other immortals (like Izana's grandma) wear masks to prevent people from noticing that they don't age, or showing weaknesses or emotions.
- Power Hair: Her haircut in the past was very short, to emphasize her authoritative position.
- Pretty Little Headshots: She's shot in the head by a crew member controlled by Ochiai, but survives.
- Really 700 Years Old: Literally. She is the oldest remaining member of the Immortal Council and has been the captain for centuries.
- Retired Badass: In the final chapter, she, Yure, and Sasaki are shown relaxing at the beach with Ochiai, having retired from their duties.
- Sugar-and-Ice Personality: She's cool, professional, and does what she must to ensure the survival of the Sidonia. But she's also got a playful side as seen by her hobby of "blending in" with the normal crew, and occasionally checks in on Nagate to see how he's doing.
- Strictly Professional Relationship: Her feelings for Saito were more than platonic, and they've transferred to Nagate. It's implied that she seduced Nagate at an onsen, though whether they slept together is never confirmed.
- The Woman Wearing the Queenly Mask: A literal example, even, as in her role as the captain she always wears an expressionless mask.
Voiced by: Satomi Arai (JP), Barbara Goodson (credited as Jane Carroll) (EN), Berenice Ruiz (LA)A female human/bear and retired Garde pilot who runs the cadet dorm (a literal "Dorm Mother"). While kind and matronly, you do not want to provoke her temper. She's another member of the original Immortal Ship Committee, and best friends with Hiroki Saito. She left the committee after Saito had a falling out with them, and later covered his escape after he swiped Nagate from the cloning faculty.
- Artificial Limbs: Lost her right arm years ago.
- Bears Are Bad News: Played for Laughs. She's actually very caring towards Tanikaze except when she's in a bad mood.
- Destination Defenestration: Dangles Izana out the window after they persuades Nagate to call her by her first name in order to break her out of depression.
- Embarrassing First Name: She hates being called by her first name, and anyone who does is quickly "encouraged" not to do so in the future.
- Emergency Transformation: She used to be human, but her central nervous system was transplanted into the body of a bear.
- I Was Quite a Looker: As seen in flashbacks, she was quite attractive before being put into the bear body.
- Mama Bear: A literal one. She's very protective of the cadets, specially Nagate.
- Never Mess with Granny: Has the air of a kind, elderly matron. She's also a bear, and a bit grumpy too. Do the math.
- Really 700 Years Old: She is almost as old as Kobayashi.
- Retired Badass: Formerly a guardian pilot and security head of Sidonia.
- Team Mom: She supports the cadets during their times of crisis, especially Nagate.
- Unusually Uninteresting Sight: In an otherwise fairly hard sci-fi series, it's a bit jarring to see a talking bear with a prosthetic hand. The only person who seems to take any notice, though, is Tanikaze, and it's chalked up to him living in the underdeck for his entire life.
Voiced by: Hisako Kanemoto (JP), Marieve Herington (credited as Lindsay Torrance) (EN), Sofía Huerta (LA)
A bright and calculating girl, Yuhata becomes a friend of Izana and Nagate after the latter terminates the Gauna that killed her brother, a member of Akai's squad. Quickly developing feelings for Nagate, she constantly competes with Izana for his attention.
Yuhata later becomes the assistant commander for Guardian operations due to her talent for battle tactics.
- A-Cup Angst: Yuhata is jealous of Izana's new and bigger knockers, and wears a padded bra to make her own appear a couple of cup sizes bigger.
- Beauty Mark: She has a mole on her left cheek.
- The Captain: Of the warship Mizuki. In the Distant Finale, he's become Captain of the Sidonia.
- Clingy Jealous Girl: She is quite possessive of Nagate, sneering behind his back when he invites Shizuka and Izana on a trip to Sidonia's ocean and trying to rig the underwater pods so that they would be left out. It backfires, and she's left stuck with Izana. Later she tries to do a Date Peepers with Tsumugi after Nagate goes somewhere for an inspection with Izana.
- Curtains Match the Window: She has green hair and eyes.
- Gender Bender: She has a sex change in order to hook up with Izana, becoming a cyborg in the process.
- Hollywood Cyborg: Yuhata becomes a cyborg like Izana in the Distant Finale.
- Innocent Cohabitation: She joins Izana and Tsumugi as one of Nagate's housemates.
- Meaningful Name: Midori is the Japanese term for green.
- Mission Control: Performs this role after being assigned to the bridge by Ichirou.
- Number Two: She becomes this to Kobayashi after Ichirou Seii returns to the field. She's later promoted to Vice-Commander.
- Official Couple: Yuhata has a sex-change and hooks up with Izana during the 10-year timeskip in the final chapter.
- Otaku: Fangirls over bits and pieces of Sidonia's military technology, and builds scale models of the Gardes. Later on, she fangirls over the Mizuki at its launching ceremony, apparently forgetting she's supposed to be on its bridge captaining it at that exact moment.
- The Strategist: Ichirou Seii, the prior Commander's Aide, takes note of her strategic brilliance and handpicks her as his successor.
- You Gotta Have Blue Hair: Yuhata has green hair.
- Young and in Charge: One of the youngest human characters and already assistant commander and later captain of the Mizuki.
Voiced by: Tomohiro Tsuboi (JP), Joey Lotsko (EN), Mauricio Pérez (LA)
- Benevolent Boss: He's quite nice and understanding towards the younger pilots.
- Custom Uniform: Has a custom helmet that covers his lower face.
- MayDecember Romance: He hooks up with Samari Ittan during the final chapter, and they have several children.
- Number Two: He was the Commander's Aide until Yuhata replaces him.
- The Strategist: He was the Commander's Aide before returning to the field, and handpicked Yuhata Midorikawa as his replacement. He also spread a rumor about how to get a chance to photosynthesize with Samari, as an effort to boost morale for the male pilots.
- Well, Excuse Me, Princess!: He has this dynamic with Captain Kobayashi.
Voiced by: Takako Honda (JP), Cindy Robinson (EN), Leyla Rangel (LA)
- Boobs of Steel: Sasaki is incredibly strong and her breasts are the largest of the female cast. They even seem to psychically hurt people smashed against them.
- The Engineer: She is in charge of repairs and developing experimental technology.
- Fan Nickname: In-universe, "Ultimate Human" by Tsuruuchi.
- Peek-a-Bangs: Her hair covers her right eye.
- Tomboy and Girly Girl: She's the Tomboy to Yure's girly girl, being a mechanic.
- Tomboyish Ponytail: She keeps her long hair tied up in a ponytail, emphasizing her brash and aggressive personality.
- Vague Age: There are hints that she is an immortal, but it is not confirmed yet.
- Wrench Wench: She is the Chief Engineer of Toha Heavy Industries, and is thus in charge of repairing the Guardians and developing and testing new weapons.
Voiced by: Rikiya Koyama (JP), Michael Mcconnohie (credited as Geoffrey Chalmers) (EN), Jesús Cortéz (LA)
Nagate's "grandfather", a legendary guardian pilot and also one of the original founding members of the Sidonia's Immortal Committee. He was the Sidonia's top Ace for centuries until 100 years ago when Ochiai deliberately abandoned all 28 Kabizashi in space, leaving the Ship defenseless. It only took him only 4 minutes to locate and retrieve the Kabizashi, but in that time 99 percent of the ship's population had been consumed by the Gauna. Finally burnt out after 500 years of service, Saito retired from piloting and stopped ingesting the immortality drugs that were keeping him young and fit. He went missing soon afterwords, and it was over 80 years before Kobayashi and Lala finally managed to locate him. In that time, old age had finally caught up to him and he was in failing health; despite this, he refused to seek medical attention or get a brain transplant into a younger body, as he simply wanted to age and die like a normal person. Kobayashi, however, was not about to let the Sidonia loose it's top ace, so she sent a sample of his cells of to the cloning labs, leading to the creation of Nagate. When Saito learned that he had been cloned a replacement body without his consent, it was the final straw. Considering Nagate his "son", he fought his way into the Cloning labs and took him out of his incubator prematurely. Kobayashi and Lala then arrived on the scene with reinforcements and tried to make him stand down, but Saito would have none of it. Declaring his intention to raise and train Nagate himself, he fought off the security team (with a little help from Lala), and then vanished into bowels of the Sidonia.
- Ace Pilot: The Sidonia's top ace for over 500 years, and the first person to kill a Gauna in combat.
- Badass Grandpa: He was an ace pilot for over 500 years, but after he stopped taking the immortality medication he aged normally. Being geriatric and in poor health didn't stop him from holding off the security team while getting baby Nagate to safety.
- Broken Hero: Ochiai's betrayal and the subsequent slaughter of Sidonia's population were the catalyst for him to quit piloting, even though he put a stop to the Gauna encroachment and was hailed as an even greater hero than before.
- Death Seeker: He stopped taking his immortality pills and refused to be cloned, wanting to die a natural death. When the latter happened anyways, he stole the clone and demanded to be allowed to raise it as its own individual.
- Posthumous Character: He's introduced as a recently-deceased corpse. It's only later on that we find out who he is and what he's famous for.
- Really 700 Years Old: He was one of the Sidonia's immortals.
- Shell-Shocked Veteran: He'd fought Gauna for 600 years before his friend Ochiai's betrayal and death of most of Sidonia's population disenchanted him.
Voiced by: Mamiko Noto (JP), Becca Ordonez (EN), Angélica Villa (LA)
Izana's grandmother and an immortal crew member. Dr. Shinatose was the scientist who managed to save Sidonia's knowledge from Ochiai's brain and devised the plan to repopulate Sidonia with genetically engineered clones after almost the whole population was killed at the end of the Fourth Defensive War against the Gauna.
- Cute Clumsy Girl: Like Izana, she's something of a klutz.
- Mama Bear: Was rather pissed to see how oblivious Takikaze was towards Izana pining after him, so she took matters into her own hands. She whipped up a fake intelligence gathering mission that involved 100 famous sites in Sidonia and he could bring an assistant, which she promptly suggested should be Izana. Then she told him that while she was fixing his neck earlier, she had implanted a bomb in his vertebrae and she would detonate it if he didn't comply. Gullible as he is, Takikaze fell for it and he ended up taking Izana on a sight-seeing date.
- Older Than They Look: She is the youngest known member of the Immortal Council and a friend of Kobayashi and Sasaki.
- Really 700 Years Old: She's a member of the Immortal Council and while not as old as Kobayashi or Lala, she is still a centenarian.
- Reluctant Mad Scientist: She is ordered by Kobayashi to complete Kanata after his psychotic breakdown despite knowing that it is wrong. Fortunately for everyone, she manages to find with Sasaki's help an alternative solution which satisfies Kobayashi.
- Sexy Backless Outfit: Normally she's in her science officer uniform as she's working almost 24/7, but she has a wilder side to her and when she saw how Izana has grown up to be the spitting image of her as a teen, she had Izana put on a white, open-backed Gothic Lolita dress that she wore in her teens while she put on a more risque black one. She then took Izana out for a trip around the town to Izana's immense embarrassment.
- Science Hero: She is Kobayashi's science adviser, the direct superior of Dr. Numi Tahiro, the head of the OSL Research Lab, and was was the one who came up with the idea to genetically engineer clones capable of photosynthesis, enabling Sidonia to repopulate and survive with heavily reduced resources.
- Shipper on Deck: She sets her granddaughter and Tanikaze up on a date by threatening him.
- Tomboy and Girly Girl: She's the Girly Girl To Sasaki's tomboy.
Voiced by: Takehito Koyasu (JP), Pete Sepenuk (EN), Julio Bernal (LA)
A member of the pilot squad who first killed a Gauna when the Kabi were found. Became a member of Sidonia's immortal council alongside Kobayashi, Hiroki and Lala. An advocate of transhumanism, he became a full-fledged Mad Scientist with a god complex over the years and became infamous for his numerous experiments with Gauna, even creating a half-human hybrid of such. Eventually, he nearly caused the destruction of Sidonia 100 years prior to the series' start, and destroyed half of the ship's accumulated knowledge, storing it in an auxiliary brain, hoping to use it as leverage so that he could keep his life.
Through Yure Shinatose's efforts, his brain was transplanted into a clone and his memories were sealed away so that the auxiliary brain could be safely accessed. Said clone now works loyally and efficiently for Sidonia, working as an intermediate of Kobayashi.
He makes a comeback when Kunato enters one of his laboratories and hijacks his body, pretending to be him. Using the Ena-copy of Hoshijiro recovered by Nagate and his knowledge, he creates a Chimera named Tsumugi. He later creates a second chimera, Kanata.
- Admiring the Abomination: He thinks Gauna are far superior to humans and wants to find a way of turning himself into something stronger via the Chimera.
- Ain't Too Proud to Beg: In the final firefight, Ochiai resorts to this. Specifically, he gives Tanikaze a What the Hell, Hero? speech for trying to destroy humanity's best chance of survival, and when that fails to sway Nagate, offers him a chance to see Shizuka Hoshijiro again. It doesn't work.
- A God Am I: A fit of his almost wasted the whole ship 100 years ago and forced everyone else to ice him. The usually good guy in the black suit is his clone.
- Ambition Is Evil: Wants to become a living god.
- Batman Can Breathe in Space: After heavy cybernetic modifications, he could go out in space without spacesuit.
- Body Surf: He uses a Blood Nematode to take over Kunato's body, then transfers his consciousness to Kanata.
- Brain in a Jar: His auxiliary brain is kept locked away in a vault so that he can't wreck havoc.
- Evil Hero: Yes, he IS evil! ...and Sidonia would have been completely wiped out about mid-way through season two if it wasnt for him.
- FaceHeel Turn: Turned on Sidonia after Kobayashi ordered him to shut down his Gauna research.
- Fallen Hero: He saved Sidonia and his comrades multiple times with the use of his scientific knowledge and inventions, but his arrogance led him to throw away Sidonia's Kabi to prove that Gauna are attracted to them, and this nearly ends up destroying all of Sidonia.
- Grand Theft Me: He takes over Kunato's body, and later takes over Kanata as well.
- I Was Quite a Looker: As shown by some flashbacks and by his clone, Ochiai used to be quite attractive before he got involved with transhumanism.
- Jerkass: Much more so than even Kunato. He enjoys being smug about every questionable thing he did, as well.
- Kick the Dog: Ochiai kills Mozuku very casually and resurrects her for one of his collaborator. Then he also kills a civilian Hot Scientist afterwards to cover up Kanata's malfunction.
- When he takes over Kanata, he has an internal monologue that he will eventually destroy Sidonia.
- Mad Scientist: He wants to become the ultimate life form, and is willing to kill anyone who gets in his way.
- Manipulative Bastard: Nobody knows he's taken over Kunato, and he's using that fact to continue his research into Gauna-human hybrids from 100 years ago.
- Me's a Crowd: There are at least two of him running around the Sidonia: one having possessed Kunato, and the other acting as Captain Kobayashi's right hand.
- Puppeteer Parasite: He does this to Kunato via his "blood nematode".
- Sealed Evil in a Can: After he was captured at the end of the Fourth Gauna Defense War.
- Shut Up, Kirk!: Belittles anyone who questions his vision of immortality.
- Smug Snake: He was Sidonia's greatest scientist. Unfortunately for everyone, his ego was even bigger.
- Transhuman Treachery: Transhumanism in general isn't a bad thing in the series, but Ochiai's heavily modified, almost monstrous cyborg body is a clear case of the dangers of going too far. His experiments with creating Chimera are an effort to turn himself into the perfect human-Gauna hybrid
- Ultimate Lifeform: His main goal is to become one.
- Well-Intentioned Extremist: Turns out really he did want to protect the people of Sidonia. His mother died protecting the Ship from the Gauna, and he swore to take up her mission. When Lala had her accident and had to be confined to life support, it gave him the idea of finding new bodies for the crew instead of finding a new home, which lead to his obsession with the Gauna. However, that obssesion became more and more twisted over the centuries and he eventually went off the deep end.
- Wham Line: He gets a few, but Its ok. I used a human baby. kind of sets the stage for what hell be like, while not contained.
- Badass in a Nice Suit: He's usually seen wearing formal attire, even when engaged in violent activities.
- Chick Magnet: He is later voted as the most popular man on board the Mizuki (among women).
- The Dragon: The Immortal Council created a clone of him to access his auxiliary brain, but Kobayashi co-oped him into being her Number Two.
Voiced by: Rina Sato (JP), Reba Buhr (EN), Cecilia Gómez (LA)
The head scientist of the OSLnote -research who is responsible for the task of observing Gauna 491's captured Ena replica. She's taken over by one of Ochiai's blood nematodes when she realizes he'd taken over Kunato's body.
- Bring My Brown Pants: Wets herself when she is taken over by a blood nematode.
- Cute Clumsy Girl: She's formally introduced tripping over her own feet and crashing into Nagate. The most obvious hint that she is taken over is she stops being clumsy.
- Empty Eyes: After the blood nematode blocks her personality.
- Genius Ditz: She has enough insight and knowledge to become Yure's second in charge. However, Ochiai considered her not worthy enough to not take over.
- Hot Scientist: She even gets a Shower Scene.
- Kill the Cutie: Killed by Ochiai to cover up the dormant Gauna he hid.
- Meat Puppet: Ochiai infects her with one of his blood nematodes, turning her into his slave.
- Psychic-Assisted Suicide: Kills herself when the Ochiai clone investigates the odd events in the OSL research.
- Teen Genius: She's not much older than the protagonists but is the head scientist at the OSL research facility.
- My Sensors Indicate You Want to Tap That: Post-Grand Theft Me, she notes Nagate's reaction to GA 491 wearing a... "sundress" and asks if he wants to enter its containment chamber for some alone time.
- Who Wants to Live Forever?: Asks Ochiai!Kunato this question, which sparks a Shut Up, Kirk!.
Gauna and Chimera
Voiced by: Aya Suzaki (JP), Stephanie Sheh (EN), Andrea Orozco (LA)
Following Shizuka Hoshijiro's assimilation by the Gauna, three Garde-shaped Gauna, dubbed GA-489 through 491, were encountered. While 489 and 491 were dispatched with relative ease, Gauna-490 displayed a sadistic intelligence and escaped to become a reoccurring antagonist, earning the moniker "Crimson Hawk Moth". GA-491's "Ena pilot" was captured by Nagate, developing a childlike personality and retaining fragments of Shizuka's memories, but was taken and impregnated by Ochiai, giving birth to Tsumugi Shiraui and Kanata. Gauna-490 became a reoccurring antagonist before being destroyed by Tsumugi and Nagate, though her Ena pilot was secured before the destruction of her true body, and was later implanted with Tsumugi's consciousness.
- Attack Hello: Once put in containment, GA-491's Ena pilot's first response to seeing Nagate was to launch a flurry of tendrils at him.
- Bishōnen Line: After regenerating a second time, the Crimson Hawk Moth emerges from the Large Mass Union Ship and sheds her Garde body to reveal a winged, skeletal version of Shizuka. After draining Tsumugi's Heigus reserves she becomes even more powerful and develops an exoskeletal appearance.
- Blade Below the Shoulder: She could extend and fire kabi blades from her wrists in her second and third forms.
- Body Horror: After being impregnated by Ochiai, 491's Ena-copy's body undergoes grotesque transformations during Tsumugi's gestation.
- Brain Uploading: Yure uploads Tsumugi's consciousness into the Crimson Hawk Moth's Ena pilot, though faint traces of Hoshijiro's personality remain.
- Breath Weapon: The Guardian portion of its body can spit crimson Higgs beams.
- Curb-Stomp Battle: The Crimson Hawk Moth easily tore apart any Garde not piloted by Nagate. Tsumugi briefly turned the tables, but the sight of the Crimson Hawk Moth's pilot Ena caused her to let her guard down.
- Cute Monster Girl: The first Hoshijiro Ena's interactions with Nagate were adorable.
- Dem Bones: The Crimson Hawk Moth's second form was skeletal in appearance.
- Doppelgänger Attack: She creates Ena replicas as a diversion during her second assault and disguises herself as Izana's damaged Garde to infiltrate the enemy.
- Energy Absorption: Gauna 490 drained Tsumugi's Heigus particle supply during their fight, and would have killed her if Nagate hadn't intervened.
- Evil Uncle: Gender-flipped: GA-490 nearly killed Tsumugi, who is the daughter of GA-491 - for all intents and purposes GA-490's twin sister.
- Expendable Clone: There were initially three Gauna who assumed the shape of Garde, dubbed Gauna 489 through 491. 489 and 491 are killed in the first confrontation, but the one named Gauna 490/Crimson Hawk Moth by humans escapes. When next seen in the manga, she leads 47 other Garde-type Gauna against an equal number of Gardes.
- Exotic Eye Designs: Gauna 490 has red eyes with a grid-like array of white pupils. In her second and third forms, her left eye has a ring of white dots framing her iris instead. In the Distant Finale, she - or rather, Tsumugi in her body - has one black eye and one red eye with a square white pupil.
- Eye Beams: Her third form could fire Heiggus particle beams from her right eye powerful enough to damage the prototype Type 20 Garde.
- Fangs Are Evil: Gauna 490's helmet has a fanged mouth on it.
- Forceful Kiss: Gauna 490's Ena pilot gives Nagate his first kiss while trying to strangle him to death.
- Full-Frontal Assault: The Crimson Hawk Moth sticks her stark naked Ena pilot into Tanikaze's cockpit in an attempt to kill him. Her third form also has chinks in its pelvic armor that strongly resemble female genitalia.
- Giggling Villain: Gauna 490 seemed to find killing its former comrades amusing, since it was laughing throughout its first sortie.
- Good Colors, Evil Colors: The Guardians are robotic and white, while the Crimson Hawk Moth is biomechanical and crimson. In the anime, the Heigus energy emitted by the Guardians is blue, whereas the energy emitted by the Crimson Hawk Moth and the other Gauna is red.
- Hero Killer: Gauna 490/Crimson Hawk Moth probably generates more human deaths than any other Gauna in the manga, wiping out a squadron and a half by itself in one sortie.
- Hime Cut: Like their template, the Garde-type Gauna have Sci-Fi Bob Haircut versions of this.
- Humanoid Abomination: The Crimson Hawk Moth and the other Garde-type Gauna were formed using Hoshijiro and her Garde as a template. Later on, the Gauna 490 transforms into a more humanoid form with Hoshijiro's face.
- Human Aliens: The Ena copies possess a replica human skeletal structure and organs.
- "I Know You Are in There Somewhere" Fight: Nagate tries this early-on with the Crimson Hawk Moth, pleading with her to stop killing their friends.
- Ironic Echo: As she's about to finish off Tsumugi, she repeats the latter's words to her when their positions were reversed.
- Law of Chromatic Superiority: The blood-red Gauna 490, code-named "Crimson Hawk Moth", vastly outperforms every Guardian pilot except Nagate.
- Lightning Bruiser: Of the 51 Garde-type Gauna, Gauna 490 was faster, stronger, and more skilled, enabling it to become a reoccurring antagonist and earning it the codename "Crimson Hawk Moth". It's even capable out out-dogfighting Nagate.
- Lovecraftian Superpower: The Garde-type Gauna were capable of projecting tentacles, firing energy beams, and shapeshifting. Their main bodies resembled a biomechanical Guardian with a skull for a cockpit, and their Ena pilots are clad in biomechanical exoskeletons resembling Guarde pilot suits. Even the Ena pilots possess a degree of this, being capable of projecting tentacles and shapeshifting clothing.
- Manchild: Guana 491's pilot Ena's activities - when not floating in midair and staring at the Kabi spear containment area - consisted of sounding out Nagate's name syllable by syllable, and writing it on the walls of her chamber. She even seemed dismayed when she accidentally snapped a felt pen with a tentacle while doing so and tried to fix it by putting the two halves together, like a child would. It makes what Ochiai did to her all the more disgusting.
- Matryoshka Object: When not floating outside, the Garde-type Gauna's pilot Enas are seated in a cockpit-like cavity within their Guardian-shaped main bodies.
- Metamorphosis Monster: After regenerating for the second time, it undergoes a metamorphosis into a skeletal, winged version of Hoshijiro. After this form is shredded by Tsumugi, she catches the Chimera off-guard and drains her Heigus Particle stores to regenerate into a fleshed-out version of her second form that's stated to be many times more powerful than before.
- Monster Is a Mommy: The first captured Ena copy is impregnated by Ochiai and gives birth to Tsumugi and Kanata.
- Now or Never Kiss: After Gauna 490 was blown in half by Nagate, it sticks its naked pilot Ena into his cockpit and kisses him in order to smother him with tendrils. Nagate's fellow pilot Tsuruuchi later snarked that he was surprised Nagate didn't jump her then and there.
- Not Quite Dead: Gauna 490 has been seemingly killed by Nagate twice, with only her True Body escaping.
- Organic Technology: The Crimson Hawk Moth's main body is a blood-red and white biomechanical replica of Hoshijiro's Guardian with a skull for a cockpit note , and its Pilot Ena is often dressed in a red organic version of the Guardian pilot uniforms.
- Past-Life Memories: While regenerating, the Crimson Hawk Moth would experience fragments of Shizuka's memories, growing stronger with each regeneration. After being implanted into 490's Ena body, Tsumugi remarks that there are still faint remnants of Shizuka's persona within her.
- Personal Space Invader: The Crimson Hawk Moth's Ena pilot invaded Nagate's cockpit, forcibly removed his helmet and kissed him.
- Put on a Bus: The first captured replica seemed to retain some of Hoshijiro's memories of and affection for Nagate, but was seized by Ochiai before that could be explored. The second replica pilot is left in Tanikaze's cockpit when the Crimson Hawk Moth is destroyed, but is put in a facility well outside Ochiai's reach. It's stated that although the Crimson Hawk Moth Pilot is a replicate of her, it will briefly regain her memory and identity when the Gauna core loses its control when rebuilding the Ena structure.
- Put the "Laughter" in "Slaughter": Aside from listing a kill score, Gauna 490 was laughing eerily while it utterly decimated every Garde it went up against.
- Red Baron: Gauna 490 earns the codename "Crimson Hawk Moth".
- Skull for a Head: The Crimson Hawk Moth's cockpit resembles a skull.
- Spike Shooter: She could fire a barrage of kabi needles from her arms.
- Sole Survivor: Of the three Garde-type Gauna, Gauna 490 was the only survivor of their first sortie and becomes a reoccurring threat until Nagate and Tsumugi finally defeat her.
- The Strategist: After the Crimson Hawk Moth was created, the Gauna became far more strategic and efficient in copying and adapting to the Sidonia's technological advances. After each of her defeats, it was noted that without her to lead them the Gauna were a far easier enemy to face.
- Tragic Monster: Shizuka Hoshijiro was Nagate's first love interest, and long after she was assimilated the Gauna created in her likeness retain traces of her human self that manifest from time to time. Chapter 21 opens with a shot of GA 490 standing in the Ocarina Mass Union Ship, with its Ena Pilot removing her helmet to reveal a sad expression bordering on a Thousand-Yard Stare.
- Twin Telepathy: 491's Ena copy had its gaze fixed on where the Kobizashi spears were stored, and the anime implies she was transmitting this intel to 490.
- Unexplained Recovery: The anime didn't show that the Crimson Hawk Moth's core had survived or her metamorphosis into a more humanoid form, skipping straight to her third form and making her reappearance more abrupt and jarring than in the manga.
- Woman in White: The first Ena copy morphs its half-destroyed combat exoskeleton into a white-and-red dress when Nagate visits it for the last time. Numinote asks if he wants to enter the containment chamber. Before what Ochiai did is revealed, that Ena is shown to have morphed a longer, more beautiful dress. Turns out that dress is just cover for the Body Horror ahead.
Voiced by: Aya Suzaki (JP), Stephanie Sheh (EN), Nycolle González (LA)
Half-human and half-Gauna, Tsumugi was created from the first Hoshijiro Ena and Ochiai's knowledge of Gauna as a chimera, a bio-weapon of mass destruction. Despite having astoundingly devastating powers, Tsumugi has an very gentle, curious, and kind-hearted personality comparable to that of a child's. She feels a connection to Nagate that is reciprocated immediately, probably because of who her "mother" is. She becomes close friends with him and Izana, and they serve to ground her and keep her from doing reckless things.
Despite being fully aware of her origins and the motive for her creation, her innocence and loyalty towards her 'father' make her one of Sidonia's greatest assets.
- Absurdly Sharp Claws: She can form artificial Kabi talons sharp enough to rip through a Gauna's true body.
- A-Cup Angst: The Crimson Hawk Moth body's bust shrinks once it fully integrates her mind, much to her dismay and annoyance.
- Action Girl: Is quite a fierce fighter due to her hatred of Gauna.
- Alien Lunch: The rice pot she cooks comes out nightmarish, with unidentifiable lumps and a fish head protruding out. It's rather literal, as Tsumugi is half-alien.
- Babies Ever After: She and Nagate have a daughter named Nodoka.
- Badass Adorable: While most considered her to be frightening at first, her interaction form is cute and her cheerful personality wins everyone over. It also helps that she's one of the strongest warriors on Sidonia.
- The Berserker: When she's badly injured during her second sortie, she snaps that This Is Unforgivable! and ignores orders to launch herself claws first into a swarm of Gauna, screaming in rage the whole while. Izana taking a bullet - or tentacle in this case - to protect her snaps her out of it.
- Beware the Nice Ones: She's friendly and loving, but extremely deadly when mad. Tsuruuchi made the mistake of teasing her over Nagate's absence when the latter was on a date with Izana, and offered himself as a replacement. Tsumugi agreed... and nearly destroyed his Garde with her insane strength and speed. When Izana was stranded on Lem VII, Tsumugi would have gone rogue to rescue her had Kobayashi not sanctioned a rescue op, realizing that she risked losing two of Sidonia's greatest assets (Tsumugi and Nagate) if she refused.
- Body Horror: Due to her ability to regenerate, she's suffered horrifying injuries taking on more powerful Gauna.
- Brain Uploading: Yure used Ochiai's mind uploading technology to implant Tsumugi's consciousness and memories into the Crimson Hawk Moth's Ena pilot.
- Bullying a Dragon: When the Guardian pilot Kouichi Tsuruuchi teases her over Nagate missing his teamwork practise, Tsumugi suggests he join her instead and almost destroys his inferior Garde in the process.
- Catchphrase: A very cheerful "Thank you so much!"
- Clingy Jealous Girl: Due largely to Yuhata, she exhibits some of this after finding out Nagate went off to a resort area with Izana alone. The two of them attempt to do a Date Peepers moment, but unfortunately she is late because of a routine exam on her body.
- Dead Person Impersonation: After seeing Nagate's reaction to the second Hoshijiro Ena after its capture, she takes on Shizuka's appearance and dresses in some of Izana's clothes to surprise him. It backfired.
- Dreamwalker: Enters into Nagate's dreams at one point and assumes the form of Hoshijiro.
- Does This Remind You of Anything?: Like it or not, her interaction form kind of looks like a dong.
- Gentle Giant: A female example, since she's the same height as the Garde but outside of combat is sweet and caring.
- Half-Human Hybrid: Is the daughter of the first Hoshijiro Ena and Kunato/Ochiai, making her half-human and half-Gauna.
- Heroic Sacrifice: She performs one in the final confrontation between Nagate and Kanata. Despite being badly damaged, she dives into the Lem system's star to help pull Nagate out of its gravity well and fuses her Ena to his Garde to protect him from the intense heat. She survives long enough to thank him for making her happy before being incinerated.
- Humanoid Abomination:
- In her original body, she was a human-Gauna hybrid and very Lovecraftian in appearance, though she's firmly on the side of humans and once people get used to her they find her charming and adorable.
- After her mind is transferred to the Crimson Hawk Moth's Ena pilot, she's completely human in form... except that her body is comprised of Ena and has access to the same Voluntary Shapeshifting abilities that the pilot Ena originally possessed, though she hasn't consciously used them.
- I Just Want to Be Normal: She wishes she could assume human form so she could stay with Nagate in person rather than using her tentacle as a proxy. She gets her wish when her consciousness is uploaded into the Crimson Hawk Moth's Ena pilot.
- I'll Kill You!: When fighting Gauna 490, she states that her sole purpose is exterminating it.
- Kindhearted Cat Lover: Fond of the cat who lives in the Shinatose residence.
- Light 'em Up: She can generate intense ultraviolet radiation from her left eye.
- Mad Scientist's Beautiful Daughter: Played quite straight, although nobody except Ochiai himself is aware of it.
- Mismatched Eyes: After her consciousness was implanted in the Crimson Hawk Moth's Ena pilot, both her eyes were initially black. Her right eye turned red with a square-shaped pupil after the Crimson Hawk Moth's body fully integrated her mind due to being covered with Ena.
- Multiple Head Case: She has a retractable tentacle in her chest that can extend to colossal lengths and is equipped with a single eye and a number of smaller tentacles. She uses it to interact with the humans on a more personal basis, and can also shapeshift it to human form.
- My Blood Runs Hot: When she becomes embarrassed — as when Tanikaze confessed to her — her skin becomes superheated.
- Person of Mass Destruction: She's powerful enough to take down regular Gauna easily. She even manages to defeat the Crimson Hawk Moth somewhat easily. It was only due to the Crimson Hawk Moth's pilot resembling Shizuka that threw her off and gave the remaining ena time to attack.
- Pink Means Feminine: In the anime her exoskeleton is pink and red, and she's quite feminine.
- Second Love: She is this for Nagate, who previously fell in love with her "mother".
- Stomach of Holding: She has a biomechanical cockpit inside her abdominal cavity that is connected to a mouth-like aperture in her tail.
- What the Hell, Hero?: Berates Kobayashi and Yure for trying to kill Kanata just after she'd gotten him to calm down.
The second chimera born from the first captured Hoshijiro Ena and Ochiai, he proved to be far more unstable than his sister. Curiosity got the better of him when exploring the research labs and he suffered a mental breakdown, blasting a hole through the hull of the Sidonia in the process. In Chapter 64, he is released by Ochiai and taken over.
- Curiosity Is a Crapshoot: Like Tsumugi, he uses his tentacle-eye to explore the Sidonia through the pipes, but comes across a lab containing his mother and presumably several other prototype chimera and has a mental breakdown as a result.
- Eye Scream: He's lacking a right eye and has a Wave Motion Gun in its place.
- Facial Horror: He has an empty socket for a right eye that can turn into a Gravity Emission cannon.
- Go Mad from the Revelation: He has a psychotic breakdown when he sees his horribly deformed mother.
- Grand Theft Me: He is taken over by Ochiai, and ultimately slain by Nagate.
- Half-Human Hybrid: He's the son of the first Hoshijiro Ena and Kunato/Ochiai, and is Tsumugi's younger brother.
- Impaled with Extreme Prejudice: Had a Restraining Bolt rammed through his head after his freak-out.
- Not Quite Dead: His Core is destroyed and he dissolves into foam... only to reveal that he has a second core and reform.
- Person of Mass Destruction: Probably more so than Tsumugi, due to possessing a Wave Motion Gun.
- Wave Motion Gun: He has a Graviton Radiation Emitter in his eye powerful enough to punch clean through the Sidonia's hull and leave a very visible hole in a nearby moon.
Voiced by: Yukari Tamura (JP)
A gynoid created by the pacifist movement who was stranded on Lem-IX. She initially blames Nagate for the deaths of the colonists and the Gauna attacks, but develops a Tsundere attraction to him after he rescues her.
- Cyborg Helmsman: She was a descent shuttle pilot of the Lem expedition and later becomes the helmsman of the new Sidonian warship, Mizuki.
- Nice Job Breaking It, Hero!: Used a Higgs Boson communicator immediately after being told it would attract the Gauna, and was attacked as a result.
- Our Nudity Is Different: When her armored mode is active she doesn't consider herself to be naked even if she's not wearing clothing. Unfortunately for her, she has very little control over when it activates or deactivates.
- Power Incontinence: She has limited control of when her armored mode activates and deactivates, causing Nagate to accidentally get a good eyeful of her naked body as a result.
- Ridiculously Human Robot: When outside of her armored mode she looks exactly like a tall teenaged girl.
- Robot Girl: She is a female android created by a pacifist out of the belief the Gauna wouldn't attack a machine.
- Tsundere: She falls for Nagate after he saves her, but is a strong Type-A tsundere about it. She breaks down sobbing and hugs him after he adopts her.
- Sole Survivor: She is the only surviving member of the Lem expedition.
- Super Mode: Her outer covering can harden itself into an exoskeleton, which she considers an alternative to wearing clothing.
- Un-person: When she was ditched by the pacifist movement she attempted to strike it out on her own, but was immediately stonewalled due to not being registered as a citizen or crew member.
- You Gotta Have Blue Hair: She has blue hair, which isn't all that unusual considering she's a robot.
- What Measure Is a Non-Human?: Initially considered not worth a rescue mission because she is not a human crew-member.
- Declaration of Protection: The sequel hook of the manga is Nodoka's statement that if Aunty Izana got into trouble she'd come rescue her.
- Half-Human Hybrid: She's half-human, half-Gauna, though she appears completely human.
- Heroic Lineage: Her father is Nagate Tanikaze, a veteran pilot and hero of the Gauna War, and clone of the prior ace pilot Hiroki Saito. Her mother is Tsumugi Shiraui, the Chimera daughter of Gauna-491 and Norio Kunato, another ace and veteran of the Gauna War - in the body of the Crimson Hawk Moth, a commander and ace of the Gauna.