The protagonist of the series. He is a normal high school student who was infected by a Parasite in his right arm. The Parasite, later named Migi, is not hostile towards Shinichi but will do anything it takes to survive and not let Shinichi endanger him.
- Accidental Pervert: Shortly after his arm is taken over in the beginning, Shinichi accidentally touches Satomi's breasts, causing her to slap him.
- Adrenaline Makeover: Starting out as little more than a flighty, somewhat lankly character type. one would never guess he'd develop from your typical bowler cut face in the crowd into a rough and wild Skull Kicker with big yin for kin killing to defend his hearth and home.
- Anti-Hero: After being healed from a mortal wound by Migi, Shinichi becomes more like this. He is still willing to protect humanity from other Parasites, but loses his human moral conscience, acts more selfish, and becomes really ruthless towards his foes. Migi on the other hand, becomes more heroic as the series progresses.
- Beware the Nice Ones Quiet Ones: Noticably a nervous and innocent boy at the beginning but as the series goes on he goes from kind and meek to stoic and ruthless. But even after his transformation Shinichi tries to be kind as possible but talks less.
- Big Eater: Becomes one after being infected with a parasite. Migi feeds himself with nutrients from Shinichi's bloodstream, upping Shinichi's need for sustenance because of it.
- Bio-Augmentation: Is no longer "fully human" due to bonding with Migi, especially after Migi heals a fatal injury and gives up part of his body mass, after which he gets superhuman abilities.
- Blessed with Suck: Also Cursed with Awesome. Sure he gets neat superhuman abilities, and actually able to fight a Parasyte on equal footing... But he's inevitably dragged in the Parasyte-vs-Parayste intrigue which caused loss of several people dear to him, and most importantly caused him to lose some of his empathy.
- Body Horror: There's a reason Migi is the trope image. Lucky for Shinichi, he only lost his hand, not his brain as Migi had intended.
- Came Back Strong: After Migi saves him from a mortal wound, Shinichi gains some of the Parasites' superhuman abilities, like increased strength and senses, minus the shape-shifting.
- Character Development: From a wimpy Ordinary High-School Student to a calm and ruthless badass who hunts down Parasites.
- Chick Magnet: It seems that every girl Shinichi meets wants a piece of him. Satomi, Kana, and Makiko, to name three in the first five episodes. As Yuko and Akiho tell each other, they'd also be after him if Satomi hadn't gotten there first.
- Cynicism Catalyst: Besides fusing himself with Migi, his mother's death at the hands of a Parasite also contributed to his personality change and him starting to go down the Anti-Hero path.
- Emotionless Boy: After fusing with Migi, Shinichi starts to lose the ability of emoting.
- Expository Hairstyle Change: Adopts an 80s "bad boy" look after his mother is killed by a Parasite.
- Good Eyes, Evil Eyes: After being revived by Migi, his eyes becomes noticeably narrower, which also signals him becoming more ruthless.
- Heroic BSoD:
- After finding out about his mother's murder and having to confront her Parasite-infested body, Shinichi goes into a full out denial, something which ultimately ends in his own defeat at the hands of the Parasite. He experiences it again when Kana is fatally wounded. This time, however, he proceeds to immediately rip the Parasite's heart out before trying to save Kana, to no avail.
- He has a major one after knowing that Gotou has wiped out Yamagishi's team and is hunting for him. Shinichi often hallucinates everyone he bumped into is the one after him, especially when Migi is asleep. Fortunately, Murano is able to snap him out of it by Intimate Psychotherapy.
- Humanoid Abomination: After Migi revives him after his post-parasite mom murders him, he becomes part parasite.
- It's Not You, It's My Enemies: If he weren't involved with the Parasites and had to constantly fight them in order to survive and save others, he and Murano would be in a much more stable relationship. He eventually has to estrange himself from her as the danger of his situation increases and she gets fed up with his unwillingness to let her know what's going on.
- Improbable Aiming Skills: He manages to take out Shimada with a rock thrown straight through the heart. From 300 meters away.
- Kick the Son of a Bitch: The beating he administers to Mitsuo after Kana's funeral when the latter angrily attacks him. Lasts longer in the manga, but in both cases Shinichi snaps out of it before he can deal any permanent damage.
- Lack of Empathy:
- After fusing with Migi, Shinichi begins to lose his capacity to empathize with others. He's still able to care about others, but he can hardly feel any other emotion besides anger when something bad happens to them. Whenever he does feel strong emotions, he is able to suppress them very quickly, something which disturbs him a lot. He also gains some Parasites' traits, such as his eyes becoming narrower, becoming quite detached, and even yelling at one point "Get out of the way, humans!". He is seen struggling quite often to remember empathetic behavior, and what disturbs him the most is the fact that he has been unable to cry ever since his mother died.
- When he captures an investigator who knows his secret and forces him into a taxi so they can go somewhere to talk, he doesn't realize why the investigator is so terrified. An ordinary human who has just been kidnapped by a guy with a monster for a hand has very good reason to be afraid that he might be going for his last ride.
- The Masquerade Will Kill Your Dating Life: Satomi knows that Shinichi has changed and is going through some kind of hell, but she's Locked Out of the Loop and he never tells her. This sends their relationship into a tailspin that's only bolstered on the occasions when Satomi sees him do something noble. Eventually, Shinichi's personality normalizes and the Parasite threat ends, allowing them to be together.
- Nerd Glasses: Has them in the anime adaptation, unlike the manga, but the final shot of the opening theme sequence shows him without them, along with said hair change. He's not particularly nerdy though. As of Episode 6, due to Migi healing and physically changing him, he no longer needs them as his sight has improved, along with his other senses.
- Nerves of Steel: Practically his defining trait after Migi resurrects him. Everyone around him comments on how he takes horrific events without crying or so much as flinching. His father even asks him outright if he's made of steel. Which, by this point...well, he pretty much is. However, he is not as immune to anger.
- Nice Guy: He's a pretty kind and sensitive guy, before fusing with Migi. Even afterward, he remains a mild example.
- Ordinary High-School Student: Started off like anyone else until he met Migi.
- Scars Are Forever: He has a scar in his chest and his back from when a Parasite impaled him in the heart. He survived only thanks to Migi. He later gets another scar above his right eye, courtesy of Gotou.
- The Sociopath: He's a heroic example but he still gains sociopathic traits after his mother dies and Migi fuses with him. He consciously can manipulate his emotions, and starts to have to act human to keep Murano from hating him.
- The Stoic: After fusing with Migi and being healed from a mortal wound, Shinichi loses all form of human emotions and becomes calm and emotionless, thus making him more effective to combat Parasites.
- Thanks for the Mammary: In the anime, he unconsciously gropes Satomi's chest likely because of Migi.
- Took a Level in Badass: It feels more pronounced in the anime because of the tweaks to his original appearance.
- Took a Level in Jerkass: Another side effect of fusing with Migi, as well as the strain of losing his mother.
- Unable to Cry: Shinichi finds himself unable to shed any tears after he is turned partly Parasite by Migi, even when his mother and Kana are killed by Parasites. He is finally able to cry again when Tamura's sacrifice for her child reminds him of his own mother.
- Unstoppable Rage: After seeing a Parasite impale Kana, he tells Migi to handle defense as he rips the offending Parasite's heart out. Even the emotionally-uninvolved Migi sounds visibly surprised that he was able to do it.
- Wake Up, Go to School, Save the World: Shinichi has to deal with the Parasite problem while also studying for his exams. Later on, however, Shinichi gradually drifts away from attending school in favor of dealing with his more supernatural problems. Because of this, he fails his university entrance exams and has to play catch-up.
- Will They or Won't They?: The parasite problem means that his relationship with Murano is in constant flux. They do.
- With Great Power Comes Great Hotness: Shinichi was average-looking kid with glasses before getting revived by Migi. Now he looks like a supermodel without glasses and with super strength and skills.
- Your Approval Fills Me with Shame: After his transformation Shinichi doesn't take it well when Migi tells him that he is starting to act more like a parasite.
Migi is the name given to the Parasite that infested Shinichi Izumi's right arm, taking over his hand. Migi is unlike most other Parasites in the series, as he didn't develop an urge to eat other humans due to not consuming the brain of his host. This also allowed Shinichi to retain his individuality.
- Absurdly Sharp Claws: In battle Migi can turn into razor-sharp blades that resemble claws.
- Blade Below the Shoulder: One of his forms is a long blade that appears to come from Shinichi's shoulder, but is actually all him.
- Body Horror: Best and brightest example in anime and manga, this side of Junji Ito. Grows eyes from Shinichi's fingers, not to mention a mouth, and takes other shapes reminiscent of The Thing only with a weird sense of humor.
- But Now I Must Go: Maybe. In the final episode, Migi states he'll be "going to sleep for a long time" and that Shinichi will have his right arm back. Further, when Shinichi thinks he missed Murano and she fell off a roof as the aftermath of the final confrontation with Uragami, Migi appears in his mind right before Shinichi realizes he actually caught her, thus he assumes Migi helped him one last time. The implication point towards Migi having gone almost entirely dormant inside Shinichi's body, but when it comes to the cognizant friend Shinichi knew him as, he might as well be gone.
- Character Development: Migi starts out as an amoral Parasite, but later develops a human conscience and emotions as the series progresses.
- Combat Tentacles: Along with forming blades, Migi fights by whipping them around.
- Evil Hand: Functionally, but more amoral than overtly evil.
- Heroic Neutral: Migi is amoral and interested primarily in its own survival. Due to the circumstances of its eating Shinichi's right hand, however, it finds itself an enemy of other Parasytes who distrust its still-living human host and quickly develops a mutualistic relationship with Shinichi.
- Humanity Is Infectious: While Shinichi becomes more ruthless, Migi begins to develop a human conscience and emotions as the series progresses.
- Jerkass Has a Point: While Migi lacks empathy and is quite amoral, he makes a valid point when he remarks that his fellow Parasytes are just feeding to survive, like any other life form, and Shinichi is only objecting to them doing so because they're eating humans. Shinichi admits he's right, but also makes the point that human life is a precious thing.
- Lack of Empathy: Migi completely lacks any human empathy or compassion and he doesn't understand those emotions in the first place. However, while he pretends to not care about humans and that he only cares about survival above all else, he is seen trying to understand Shinichi and takes some actions which most Parasites wouldn't even consider (such as sparing the life of Kuramori and delivering a very impressive speech in which he explains how Shinichi's life became miserable and that the P.I. should try to understand him, something that Shinichi finds quite odd coming from him), which can imply that he is actually developing some kind of empathy. He wants to protect his host in order to survive, but is seen actually caring for Shinichi (in his own roundabout way).
- Meaningful Name: Migi means "right" in Japanese. Though he's not named yet in the first episode, he keeps telling Shinichi to go "right".
- My Sensors Indicate You Want to Tap That: He thinks that Shinichi "wants to mate" with Satomi and tries to stimulate his sexual organs in response.
- No Biological Sex: The Parasites have no apparent secondary sexual characteristics, it's not clear if they can even reproduce by themselves, and Migi is referred to as "he" more out of convenience than anything. In the anime Migi is voiced by a woman, though it's high-pitched enough to be ambiguous, and a dog Parasite is voiced deeper by a man. This is unusual as the Parasites are supposed to take over humans and adopt their voices.
- Pragmatic Hero: Migi only acts to preserve his own life, and that happens to be helping Shinichi fight the other parasites.
- Shapeshifter Weapon: As with all Parasites, he can become many kinds of weapons.
- Special Odd Hand: Migi failed to infest Shinichi's head, so he took over his right hand instead. Migi has many special powers, such as Combat Tentacles and shapeshifting.
- The Stoic: Usually talks in the same tone of voice. He also feels nothing about killing his own kind to survive, and this makes Shinichi uneasy.
- Super Strength: Shinichi saves a girl from getting run over, awakening his parasitic hand in the process which is strong enough to stop a moving car. Later Migi is strong enough and quick enough to perform a Bare-Handed Blade Block to a knife and even break it.
- Supreme Chef: He seems to be very good at cooking in the movie adaptation.
- The Symbiote: Never intended to become one, but botched the initial takeover. Notably, Migi sustains himself on the nutrients in Shinichi's blood, leading to Shinichi having an increased appetite to compensate.
- Took a Level in Kindness:
- Thanks to being fused with Shinichi, Migi developed some form of human conscience and emotions.
- Close to the finale, Migi finally develops empathy and after briefly sharing a body with the Big Bad Gotou, Migi requests that Shinichi be the one to kill him since Migi can't actually bring itself to carry out the deed.
- Tranquil Fury: Despite Migi not having the capacity to show emotion, Shinichi notices that something feels a little off when Migi defends Shinichi when Kuramori demands that he turn himself over to authorities for the good of humanity.
- What Is This Thing You Call "Love"?: He fails to understand why Tamura didn't save herself and instead chose to protect her child.
Characters associated with Shinichi
- Disappeared Dad: In the movie adaptation, he is nowhere to be found.
- Drowning My Sorrows: Turns to the bottle after Shinichi's mother dies.
- Good Parents: Eventually levels with Shinichi, and while he's partly out of the loop, he does know about Parasites and trusts his son when he says it's time to get out of the house and hide.
- Secret Secret-Keeper: In his Day in the Limelight story in Neo Parasyte F, we find out he knew for a while that his son's hand was infected by a Parasite, but he trusts Shinichi enough to wait until he's willing to tell him himself.
- Weirdness Censor: He initially accepts the explanation that his wife being killed by a Parasite was just a nightmare, as the truth is too painful for him.
- And Then John Was a Zombie: A Parasite whose host body died ends up cutting off her head and using her body as a new host at the end of her and Kazuyuki's vacation.
- Crippling Overspecialization: The Parasite that takes over her body tends to go for the heart in battle, which Uda's Parasite exploits to outwit it.
- Death by Origin Story: Her death drives Shinichi towards actively hunting and killing Parasites.
- Good Parents: She's a kind and loving mother to Shinichi.
- Heroic Willpower: In the live action adaptation, she is taken over by A, yet still actually saves Shinichi from one of A's killer blows, which gives him the opening to kill both her and A for good.
- Parents Know Their Children: She knows that something is going on with Shinichi and that he's not entirely her son.
- Scars Are Forever: She suffered horrible burns on one of her hands protecting Shinichi when he was messing around the stove as a child. It continues to be a source of guilt and shame for Shinichi even into high school.
Shinichi's best friend and sometime companion.
- Armor-Piercing Slap: Gives it to Shinichi when he accidentally touched her breast.
- Betty and Veronica: The Betty to Kana's Veronica because she is a friendly and familiar classmate.
- Damsel in Distress: In the very last arc of the manga and anime she's taken hostage by Uragami the serial killer.
- Intimate Psychotherapy: Gives one to Shinichi when he has a major Heroic BSoD due to Gotou hunting him down.
- Kirk Summation: She does this to Uragami in response to the latter's motive rant.Satomi (to Shinichi, while being held hostage by Uragami): "You don't need to listen to this jerk. How can he be considered a normal human being?! (to Uragami) You're even worse than those monsters!"Uragami: "You were so scared, you couldn't even talk, and now look how spunky you are."Satomi: "I'm not scared of you! I've been through much worse at school!Shinichi: "S-Satomi..."Satomi: "Both Izumi-kun and I have gone through it. That's right. Izumi-kun, you were amazing when it all happened. You carried me and protected me with everything you had. Sure, you might not be "normal," but you're human! Humans think all life is precious! (to Uragami again) You're the monster, jerk!"
- Locked Out of the Loop: She has no idea of all Shinichi has been through since Migi infested his right arm, which damages their relationship. Migi makes sure she stays out of the loop by threatening to kill her if Shinichi brings her in.
- Muggle Best Friend: She is good friends with Shinichi but she is clueless about the existence of Parasites.
- Single Woman Seeks Good Man: She was attracted to Shinichi's Nice Guy personality. His sudden change to a more aggressive and insensitive person makes her really uneasy.
- What the Hell, Hero?: Calls Shinichi out for his increased callousness after he's merged with Migi.
- Will They or Won't They?: With Shinichi. They are in an unstable relationship because of his sudden personality change and her being Locked Out of the Loop. They will.
- You Monster!: Satomi finally calls Uragami out on that due to his inability to understand the value of human life.
Yuko is Shinichi's classmate and Satomi's friend. Her older brother is a police sketch artist, from whom she learns about the existence of Parasites. She develops a crush on Hideo after he enrolls in their school, before discovering his true nature.
- Action Survivor: She throws a glass full of chemicals at Hideo's head to protect herself.
- Ascended Extra: She has a bigger role in the anime than the manga.
- Shipper on Deck: Has hints of this in regards to Shinichi/Satomi in the anime, particularly in the beginning when she contributes to mending fences between the two after Satomi slaps Shinichi in response to the latter grabbing her breast.
- Too Dumb to Live: Leading the person you suspect to be a Man-Eating parasite into a secluded room so you can just ask them not to kill people anymore? The plan could have used some work.
- Unwitting Instigator of Doom: Yuko revealing to Hideo that she knows he is a Parasite leads to the deaths of 17 people at Shinichi's school.
Kana is a disobedient "bad girl" who develops a crush on Shinichi. She is attracted to him because of his sensitive personality, and because she can sense something "different" about him.
- Adaptation Personality Change: In the anime she comes across more as a spoiled girly girl than a delinquent. She had a noticeably rougher personality in the manga, including a smoking habit and wearing boyish clothing. At one point in the manga Shinichi even refers to her as a "sukeban" girl.
- Betty and Veronica: The Veronica to Murano's Betty because she is a "bad girl", a delinquent and has habits like smoking.
- Died in Your Arms Tonight: After being fatally injured by a Parasite, she dies in Shinichi's arms.
- Doom Magnet: It's heavily implied that her intense desire for Shinichi to be able to sense her the way she can sense him is the reason her abilities start producing a signal that other Parasites can detect.
- Dreaming of Things to Come: In her dreams, she's chased by monsters shaped like humans but have no heads. The last thing she sees is Shinichi, holding her in his arms after he's killed the monsters. This is almost exactly what happens when she's killed; "almost" because she's dying in real life.
- HeelFace Turn: Is introduced as a delinquent girl who is Mitsuo's girlfriend and effectively part of his gang. When Shinichi intervenes in the gang's beatdown of Nagai, she calls him a weakling and a poser. However, she also stops Mitsuo from beating up Shinichi in their first encounter and immediately senses that he is different. In the anime she apologizes to Shinichi for her actions on the same day.
- Hoist by Her Own Petard: Her ability ultimately leads to her death when she tries to track Shinichi down and instead, runs into a random Parasite that kills her.
- Hopeless Suitor: Has this realization when she sees Shinichi and Satomi kissing after their date in episode 11. It doesn't last, though.
- Hope Spot: Experiences this when she sees Shinichi - right hand transformed - at the doorway while running from the Parasite. Right then she gets skewered.
- Impaled with Extreme Prejudice: How she is killed.
- Love Makes You Dumb: Or ignorant. Shinichi repeatedly implies and warns her about the parasite threat, but she always shrugs all of those warnings off in the account that Shinichi gives off a different signal and that she can genuinely track him down from afar. Sure enough, not even the strand of hair she got from him helps her find him, and instead she spots a random parasite host that kills her just before she sees Shinichi.
- Morality Pet: To Mitsuo. His love for Kana is his one redeeming trait, as well as his anger at Shinichi for failing to protect her. Too bad she's only interested in Shinichi.
- Spider-Sense: She can somehow sense Parasites, though she doesn't know what they are. Later on she also develops the ability to emit a signal that Shinichi and the Parasites can detect, though it is a weaker variant of the Parasites' own signal. This latter ability is also what leads to her death.
- Stalker with a Crush: To Shinichi, as she keeps seeking him out due to her ability to sense him from a distance. She also keeps one of his hairs and later wears it as a ring on her finger.
- Thinks Like a Romance Novel: She's convinced that her power is an ability to sense her soulmate, even when she begins to notice it doesn't always lead her to Shinichi. She also has recurring dreams of Shinichi as her Knight in Shining Armor who comes to save her from monsters. What she seems to ignore (or not mind) is that the Shinichi in her dreams always rides a Parasite-corrupted horse, and his 'sword' is his shapeshifted right hand.
- Too Dumb to Live: She's so blinded by her obsession she repeatedly ignores Shinichi's warnings about how dangerous Parasites are and even lies to him about being able to distinguish between him and hostile Parasites. Even worse she tracks down a Parasite via its aura, believing it to be Shinichi. Predictably this leads to her death.
- Wrong Context Magic: She's a human with the power to sense Parasites and emit a signal on their wavelength. No explanation for this is given.
Kana's boyfriend and a leader of a small gang of delinquents.
- The Brute: Never decides to talk things out, his first reaction is always to hit.
- Can't Catch Up: On his first appearance he beats up Shinichi without much effort (though Shinichi is also hampered by having to keep Migi from slaughtering Mitsuo and everyone else). When they meet again, he is completely outclassed by a new and improved Shinichi.
- Decoy Leader: It's revealed in the manga and anime that Yano is the real leader of the gang. They are flabbergasted when Shinichi calls him out despite never having met him.
- Green-Eyed Monster: Once Kana becomes interested in Shinichi.
- Jerkass: Portrayed as this every time he appears, though after Kana's death he is shown that he actually had a Heart Of Gold somewhere inside.
- What the Hell, Hero?: Calls Shinichi out for his failure to protect Kana, as well as his emotionless behavior at her funeral.
- What Happened to the Mouse?: Does not appear again after Kana's death.
- You Don't Look Like You: His design from the manga was the most radically changed for the anime.
- Canon Foreigner: Is exclusive to the anime.
- Those Two Girls: She and Yuko are this for Satomi.
- Butt-Monkey: Ends up being this in the anime. In addition to getting the crap beaten out of him by Mitsuo and his gang, he's also beaten up by Shinichi - or rather, Migi - and Hideo.
- Green-Eyed Monster: In the anime he is the jealous student who challenges Shinichi to a fight over Satomi. It doesn't end well for him.
- HeelFace Turn: After Shinichi stands up for him when Mitsuo's gang is beating him up, he along with Kamijou and numerous other students pull a Big Damn Heroes for Shinichi and Satomi when they're being harassed by Mitsuo's gang. While he still demonstrates some green eyes when it comes to Shinichi's relationship with Satomi, he's overall more amicable with Shinichi, and even tries to intervene when it looks like Hideo is trying to start something with Shinichi.
Uda is, like Shinichi, a human who had a Parasite merge with a part of his body other than his brain.
- A Dog Named "Dog": His parasite is simply known as Parasite.
- Beware the Silly Ones: He's an overweight crybaby with a ridiculous-looking infestation, but he's still a Parasite host, and the location of his passenger means that he's a remarkably durable one. His Parasite can protect his neck with ease and he survives what should be a mortal injury to the chest because his Parasite moved his organs around.
- Blush Stickers: The only character to have them, added for the anime.
- Facial Horror: Downplayed from the infectee norm. Yes, he's got most of his face and torso replaced by a Parasite, but he's the heroic Plucky Comic Relief, so Jaw's transformations tend to look more silly and cartoony than horrific.
- He Will Not Cry, So I Cry for Him: When he hears from Shinichi what happened to his mother, Uda weeps inconsolably while Shinichi is far more muted.
- Hollywood Drowning: Averted; he fell from a cliff into the sea when the Parasite burrowed into him, and he quickly sank like a stone. It was forced to merge with his jaw and chest organs to enable them to breathe.
- Nice Guy: Uda is dweeby and overly-sentimental but he's a friendly, well-meaning man with a good heart. This is best seen with his willingness to help Shinichi even after having only known him for a couple days.
- Put on a Bus: Justified as he lives in a different part of Japan.
The Parasite lodged in the lower half of Uda's face and extended to his chest. Uda's Parasite originally does not have a name, but is later named "Jaw" (Joe in the anime).
- A Dog Named "Dog": In the anime, Uda's Parasite is just called "Parasite" (in English) when they're introduced.
- Foil: Jaw/Parasite acts more jovial than the stoic Migi.
- Heart Is an Awesome Power: Literally! The Parasite may be placed in a rather awkward position, but the control over Mamoru's vital organs prove useful in cheating death.
- Learnt English from Watching Television: Whereas Migi educated himself by reading books (and in the anime, surfing the net), Jaw/Parasite just watched TV. Uda is such a couch potato, that he says he didn't have much choice.
- Life-or-Limb Decision: In a way. When he burrowed into Mamoru, the shock of the event caused him to fall into the ocean. Once he realized that the man was drowning, he gave up on taking the brain and the whole body with it, choosing the cardiopulmonary system to ensure both their survival.
- Playing Possum: In a battle with another Parasite who took over Shinichi's mother, Jaw/Parasite made it think they were dead, and bid its time before finishing it off when it was distracted by Shinichi.
A female student who befriends Shinichi during his brief stay in Sakurazaki. Her family owns the hotel that Shinichi lodges at as he visits his hospitalized father.
- Demoted to Extra: Makiko's subplot of being stalked by one of her teacher's does not get adapted in the anime.
- Hopeless Suitor: Though not for a lack of trying, Shinichi was too distracted by everything happening in his personal life and was oblivious to her advances.
- Nice Girl: Takes it upon herself to show Shinichi around Sakurazaki and is concerned about his well-being.
- Put on a Bus: Due to the fact that she lives in a completely different city than Sakurazaki, her role in the story ends once Shinichi's father is finally released from the hospital.
- Suspiciously Similar Substitute: Makiko's brief role in the story is almost a near duplicate of Satomi's, trying to get Shinichi to open up about what's troubling him, while being Locked Out of the Loop.
- Undercover as Lovers: In the manga, Makiko's initial motivation for approaching Shinichi is to try to discourage one of the teachers from her school from stalking her.
A Private Detective hired by Reiko to spy on Shinichi and caught by Migi when he takes pictures of them. When his assistant Taro goes missing, Shiro asks Shinichi to find him. They encounter one of Hirokawa's Parasites in an underground parking lot that serves as one of their protected "dining areas." He records the ensuing fight between Shinichi and the Parasite, which thoroughly unnerves him, making him decide he wants nothing more to do with Shinichi and the Parasites.
- Beware the Nice Ones: Is pretty mild-mannered, as well as a tad clumsy. However, he is also very good at his job, and he ends up giving an enormous amount of information to the authorities that ultimately results in the raid on City Hall in retaliation for his family's murder. He also seeks revenge on Reiko Tamura by kidnapping her baby.
- Crusading Widower: His family is killed by Parasites, causing him to reveal everything he knows to the authorities before kidnapping Reiko's son in retaliation.
- Dumbass Has a Point: He does and says a number of gravely unwise things throughout the story, but he has occasional moments of clarity. He decides to stop researching the parasites after seeing Shinichi battle one to the death, accurately reasoning that he's ill-equipped to grapple with them due to being an ordinary, defenseless human.
- Dying as Yourself: Slips back into his detective persona in his last moments, telling Hirama and the cops how to identify Reiko, as well as admitting his relief that he didn't harm the baby.
- Friend to All Children: In the movie adaptation, he is very nice to his own daughter and Ryoko's son. He even plays peek-a-boo with the latter!
- I Have Your Wife: He attempts to avenge his family by kidnapping and killing Reiko's baby in front of her.
- Impaled with Extreme Prejudice: When he attempted to kill Reiko's baby.
- Oh, Crap!: He was expecting Reiko to either casually kill him or back down from threatening her child. Instead she ran him through to protect her baby, and both of them are surprised by this.
- Trauma Button: Develops one when someone mentioned "Parasite" in front of him after his family was murdered.
An elderly woman who takes Shinichi in after he gets seperated from Migi during his fight with Gotou.
- Nice Girl: She is said to have a sharp tongue, but is very kind hearted. She cared enough about Shinichi to try and stop him from leaving and getting himself killed.
Police associated characters
A veteran detective who first suspected Shinichi for Kana's death.
A military man assigned to the Parasyte Extermination Squad.
- General Ripper: Not a general, but he's committed to destroying the parasites at the cost of numerous civilian and military casualties.
- Good Scars, Evil Scars: Has one across his eyebrow.
- Off with His Head!: He is beheaded by Gotou.
- Oh, Crap!:When he found that Gotou had wiped his team out upon reaching the rooftop, and all of his weapons were useless against him.
- Sociopathic Soldier: Yamagishi is a soldier, not a cop, and the raid on Hirokawa's building demonstrates why you don't use soldiers for police work under any kind of normal circumstances. His objective is not to preserve civilian lives, but to eliminate the enemy. The moment things start to go south, he orders every civilian in the area to cooperate or he'll shoot to kill, and his soldiers willingly shoot through a Human Shield to exterminate a Parasite. The attached police express serious reservations at his willingness to casually kill people.
A serial killer who mysteriously has the power to sense Parasites.
- A Date with Rosie Palms: His reaction when seeing a pretty girl at the research lab.
- Ax-Crazy: A psychotic monster who enjoys nothing more than rape, cannibalism and murder - in various orders.
- Big Bad Wannabe: He's no Gotou. He's not even a Parasite, nor is he a Badass Normal. When he tries to get Shinichi to call him a "real human," Shinichi kills him with one punch.
- Dirty Coward: He has a penchant for killing and raping humans, but once he sees a Parasyte reveal its true form for the first time, he runs away and screams in terror.
- Early-Bird Cameo: While he doesn't appear in the manga until much later, he makes a brief appearance at the end of the first episode of the anime.
- Even Evil Has Standards: Gotou terrifies him.
- Evil Cannot Comprehend Good: Does not understand why the rest of humanity isn't as "honest" with their true natures as he is.
- Humans Are the Real Monsters: With his psychotic sadism, Uragami actually manages to be worse than the Parasites.
- Knife Nut: Emphasis on "nut".
- Lack of Empathy: He sees nothing wrong with killing people or having sex with dead bodies. In fact, he enjoys both of it.
- Messy Hair: In the movie adaptation. It is a bit weird why his hair is not shaved as a prisoner...
- Not Me This Time: He got caught prior to the story after he came across the aftermath of a parasite's feeding session and police walked in on him examining it. He slips up when he states he didn't do it "this time", causing one of the officers to remember his face from a wanted poster.
- Not So Different: A few times he's compared to a parasite. He was initially intrigued when he started to realize a few of the people around him were some new species that was infiltrating humanity, but when he found out they just do the same thing he does, he was disappointed.
- Paper Tiger: Implied by Shinichi when Satomi is held hostage, compared with Gotou.
- Post-Climax Confrontation: After Gotou has been killed, Uragami appears to take Satomi hostage, creating one final conflict before the work finishes, though admittedly of much less of a scope than the previous ones.
- Spider-Sense: He also can somehow detect Parasites. The manga, at least, implies that he does this simply by expertly unconsciously reading human body language and facial expression to identify other sociopaths or humanoids with killer instincts.
- Villainous Breakdown: Upon encountering Gotou, he completely loses it when he senses just how terrifying Gotou truly is and runs away in a panic.
Other Parasites and related characters
People associated with Reiko Tamura
Originally Ryoko Tamiya, one of Shinichi's high school teachers who is also infested by a Parasite. After she kills Ryoko's family, she goes missing and resurfaces under the name Reiko Tamura. She has scientific inclinations, and is driven to discover the biology, origin, and purpose of Parasites.
- Abusive Mom: Downplayed, and ultimately subverted, but we sometimes see her carrying the human child she bore around by dangling it by its clothes, and only had a kid to find out what would happen if two Parasites with human hosts had a kid. Justified, in that she has no human maternal instincts at all and honestly did not think she would end up having a kid.
- Action Mom: She eventually has a kid with another Parasyte, but is still capable of literally tearing people apart.
- Anti-Villain: At her core, Reiko isn't evil, just has such total Blue and Orange Morality and has no idea how to relate to humans that she is a danger to them. And unlike other Parasites, she seeks to overcome her distance from them.
- Berserk Button: In the movie adaptation, she becomes very mad at her colleagues when they killed Kuramori's daughter.
- Curiosity Causes Conversion: Reiko's strong interest in humans, her kind, and emotions in general lead her to become more human, and grow to care for her son.
- Character Development: Much like Migi, Reiko slowly develops a human conscience over the course of the series.
- Desperately Looking for a Purpose in Life: She's usually questioning why she and her kind were born and what's the purpose of their existence.
- Evil Genius: Parasites are noted for their rationality but Reiko Tamura stands out as many other characters make note of how intelligent she is. In addition to being one of the more philosophical and inquisitive characters, she also shows off her scientific abilities by merging five parasites into one body to create Gotou.
- Evil Teacher: Not exactly evil but she does do horrible things to understand Parasites and humanity.
- Fangs Are Evil: Her teeth sharpen out when in attack mode.
- For Science!: Had sex with another Parasite-infected human to see what would happen if she got pregnant. She's intrigued when the resulting child is fully human. She also doesn't kill Shinichi, despite him knowing too much, because of his unusual symbiotic relationship with Migi and especially when she senses he himself is no longer completely human.
- Go Out with a Smile: She dies with a satisfied smile, having found a purpose to her existence and entrusted her human child to Shinichi.
- Handbag of Hurt: How she finishes Kusano in a three-against-one fight.
- The Heavy: While she isn't Big Bad of the series, she certainly had the greatest influence on the story, being directly or indirectly responsible to many of the key events that happened during the course of the series. Some of these advents include A's attack on the school and having both Hideo and Shiro spy on Shinichi. Also, she was one that convinced the other parasites to follow the human, Takeshi Hirokawa, and was the one who created Gotou.
- Humanity Is Infectious: From the start, she made more of an effort than other parasites to blend into general society (mainly to not call attention to herself), and the more she studies and tries to understand humans, the more human she behaves. She also does things like training herself to laugh and discovers that she is able to laugh naturally, something which she didn't expect. She also initially had no plans to do much with her child besides use it as a science experiment and would carry him around by dangle him by his clothes; later on, she's seen holding him in a more maternal way, and even breast-feeding him. Her understanding of humans leads her to correctly guess that Kuramori would take action now that the private investigator has nothing to lose after other Parasites slaughtered his family. It is also very subtle, but in the anime her expressions become more and more human with time passing, as her eyes become ever so slightly less narrow, making her looks more natural (while the opposite happens to Shinichi after Migi saved him from a fatal wound). Her becoming more human actually sets her apart from the other Parasites, who begin to wonder if she is still one of them, and ultimately lead them to attack her after they decide that her reasoning and actions make her a threat to their group.
- Lack of Empathy: Played straight initially. As a parasite, she doesn't understand humans in general, and has a very cold and rational mind. However, what makes her different from the others is that she is actively trying to understand humans, displaying curiosity and seeking answers. It is what makes her bear a child in the first place, and she is seen going to the university in order to attend classes and assimilate knowledge. This trope is then played with as she begins to develop human emotions.
- Mad Scientist: She's the one who actually tries to understand how Parasytes and humans work, leading to her becoming a mother to test out the effects of Parasyte sex, and she's also responsible for the creation of Gotou.
- Mama Bear: She kills Kuramori for threatening to kill her baby as part of his revenge, surprising him and herself in the process.
- Maternally Challenged: Reiko does not know anything on how to raise a child, so she tends to do things like carry her normal human son around by dangling him by his clothes. Justified, as she's not even human, and moreover, she had no desire to even really parent her son initially. She does get better as time goes on.
- Noblewoman's Laugh: She develops this after learning how to laugh.
- Parental Neglect: She eventually gives birth to a human baby, but she treats him as an experiment and doesn't express any maternal love for him, even trying to use her baby as a shield against Shinichi."I'll just have to use this child as a shield."
- Prehensile Hair: Through her parasitic abilities, the hair on her head can turn into bladed tentacles sharp enough to slice off limbs completely. Or shield her kid when she's filled with lead by the police.
- Put on a Bus: For a short period of time, she lies low after giving birth to her son.
- Silk Hiding Steel: Appears to be a harmless, poised, soft-spoken woman. In actuality she is the second- or third-deadliest Parasite in the series, behind only Gotou and possibly Migi. She is an excellent tactician, an expert on Parasite physiology and behavior, and exhibits a far higher level of control over her abilities than her brethren. She defeats 3 other Parasites on her own by separating her body into two and coordinating a battle on two fronts simultaneously, exploiting their predictable behavior and instincts.
- Snow Means Death: She's killed as snow begins to fall in the park. The somber but serene weather sets a peaceful tone to her death, as she was able to find her conscience and get Shinichi to take her child to be raised in the comfort of humans.
- Surrounded by Idiots: Exhibits this attitude towards the Parasites who slaughtered Kuramori's family.
- Take Care of the Kids: In her final moments, she entrusts her baby to Shinichi and asks him to make sure her baby is raised by humans and lives a normal life.
- That's an Order!: According to her, she and all Parasites are instinctively driven to devour mankind.
- Weak, but Skilled: Another Parasite indicates that her muscular strength is not as great as his. However, she shows more control over her form and her abilities than any other Parasite, even Gotou or Migi, allowing her to kill three attacking Parasites through a stratagem involving splitting her own body and turning them against each other.
- What Is This Thing You Call "Love"?: She's genuinely shocked when her host's mother sees through her farce.
A Parasite who took over a man. Because he never bothered to learn his host's identity, he goes by the name "A". He is introduced by Ryoko Tamiya to Shinichi and Migi as the father of her child.
- Ax-Crazy: A is unstable and violent even by his species' standards. While the other Parasites at least try to be subtle and avoid taking unnecessary risks, and can sometimes be negotiated with, A only thinks about eating humans. He violates the truce arranged between Ryoko Tamiya and Shinichi and decides to attack the latter at his school, in broad daylight, in front of hundreds of potential witnesses, just because Shinichi could perhaps represent a threat.
- Dumb Muscle: Described as not too smart but he's still dangerous.
- Fatal Flaw: He only thought of humans as food, not realizing they could also pose a danger. This leads to his downfall when he fights Shinichi and Migi.
- Foil: To Reiko in several ways. For one thing, he has no desire to even try hiding himself, kills indiscriminately and is little more than an animal wanting to eat.
- Glorified Sperm Donor: He, or rather his body, is the father of Reiko's child, but they feel no attachment to each other as she only convinced him to do it For Science!.
- Impaled with Extreme Prejudice: While he has his full attention on fighting Migi, Shinichi stabs him with a metal chair leg, which leads to a lot of blood loss since it's hollow.
- Impersonating an Officer: In the movie adaptation, before taking Nobuko's body.
- One-Letter Name: Just "A", as he doesn't care enough to maintain a human identity.
- Only Known by Their Nickname: We never learn his host's original name.
- Stuff Blowing Up: Mortally wounded, he tries to find Ryoko Tamiya to try to switch to her body, but she rigs some gas tanks to blow him up.
Hideo is a Parasite with a teenager's body who decides to integrate with human society. Hideo enrolls in Shinichi's high school and expresses a desire to become friends with Shinichi, who does not trust him.
- Bishōnen: A trait he exploits to get female victims close to him. Indirectly, this causes Yuuko to fall in love with him until she finds out through many hints he's not what he seems.
- Body Horror: Justified because of his parasyte, but then he's unable to hide it when being sprayed by paint thinner that keeps him from hiding his real appearance.
- Cornered Rattlesnake: Being sprayed by paint thinner while his head transmogrified had some really nasty side effects that stunned him and injured his internal organs so much that he was forced to desperately wander around and risk being found out, as he couldn't turn his head back to normal. During this time, it is not...pretty what he does until Shinichi and Migi take him down.
- He Knows Too Much: Hideo's reaction when Yuko confronts him at school, revealing she knows his secret.
- Honey Trap: He attracts his female victims by using a bishonen face.
- Kick the Son of a Bitch: He beats up Mitsuo in the public restroom and threatens to "end him" should the latter pick a fight with him again.
- New Transfer Student: His cover.
- Vegetarian Vampire: Hideo claims that he subsists on a diet similar to that of humans, but this is shown to be a lie to gain Shinichi's trust.
People associated with Hirokawa (Unmarked Spoilers)
Takeshi Hirokawa is the elected mayor in East Fukuyama City. He leads an organization of parasites.
- Big Bad: He uses his position as mayor to create feeding zones for the parasites and increase support for them. His plan and position of power are the cause of all the problems Shinichi and Migi face.
- Boomerang Bigot: He firmly despises humans, and believes that the parasites' existence is as so to take the rest of humanity down a step on the food chain as prey. This is all despite him being a human himself.
- Corrupt Politician: He gets elected to the mayorship of East Fukuyama City running under the campaign of locally-based environmentalism, but has other, darker motives when in power.
- Disc-One Final Boss: After he's killed, the show still has three episodes to go and there's still the matter of dealing with Gotou.
- The Face: Is the public leader of the political party promoting environmentalism, and provides an umbrella for the parasites to organize and be protected under.
- Face Death with Dignity: When he realizes that the game is up, he chooses to remain in the council chamber and wait for Yamagishi's troops rather than try to escape.
- Gaia's Vengeance: He interprets the arrival and existence of the parasites' as a means to to cull the human population, standing one step above them on the food chain. This is the core of his doctrine as a radical environmentalist, believing that this is punishment for humanity's treatment of the Earth and its resources. His Humans Are Insects Motive Rant before his death best illustrates these beliefs.
- Human All Along: This is ultimately revealed by the state of his body at death, after he is gunned down by Yamagishi's troops.
- Humans Are Insects: The core of his Motive Rant in Chapter 55, before his death by Yamagishi's troops.
- Knight Templar: Firmly believes that humans are irredeemable for the damage they have caused to the planet and that parasites are righteous to devour the polluters. Hirokawa's hatred of humans is so absolute that he believes only by killing every last one can Earth be avenged for their injustice.
- Manipulative Bastard: His convincing the people of East Fukuyama City to elect him was only done so he could get in a position of power to let the parasites kill and eat them.
- Mayor Pain: As the mayor of East Fukuyama City, he enables the parasites under his command to secretly devour humans, even designating special 'dining areas' where they can all feed.
- Misanthrope Supreme: Believes humans deserve to die for how poorly they have treated the environment.
- Non-Action Big Bad: Despite being the undisputed leader of the parasites, he is never seen actively attacking Shinichi, or even feeding on humans himself. This serves to foreshadow his true identity as a human, not a parasite.
- Walking Spoiler: He's introduced as a "parasite" running for the position of mayor but it isn't until much later in the series that we discover his plans or that he is actually leading the parasites in East Fukuyama City.
Miki is a Parasite in the organization led by Takeshi Hirokawa. He is in fact one of five parasites within a single body, created originally as an experiment by Tamura Reiko. He can control three of these parasites in his host body.
- Affably Evil: Miki is much more charming and easy-going than the other parasytes, even when he's talking to just them and presumably isn't putting on an act. He's also genuinely interested in how human interactions work, as well as the unique partnership that Shinichi and Migi have. He asks them to educate him on how they fight together in the midst of battling them. Miki's friendly tone never wavers, even after he's defeated by the duo and forced to swap out with Gotou.
- How Do I Shot Web?: When acting as the leader of the quintet of parasites within his host body, Miki is noticeably inexperienced, even constantly tripping over his own legs, since he can't fully yet control the parasites in each of those limbs.
- I Am Not Left-Handed: There are actually five, not just three parasites within his host body, as Shinichi and Miki unfortunately discover.
- Leader Forms the Head: Only Miki, along with Gotou, may lead all five parasites and thus act as leader by being the head - though only Gotou, not Miki, can unify them to fight together as one.
- Meaningful Name: The name "Miki" (三木) means "three trees" in Japanese, hinting at his ability to control up to three parasites within his host body. It's also very similar to "Migi", and he matches Migi's right hand when Gotou is in control.
- Red Oni, Blue Oni: He's chatty and jovial, even in the midst of battle, in comparison to the humourless, stoic Gotou.
- Screw This, I'm Outta Here!: Miki attempts to liberated himself from Gotou's body after Shinichi poisoned Gotou by stabbing him with a rusty pipe.
- Uncanny Valley: Deliberately invoked and discussed by the other parasytes. Unlike his placid compatriots, Miki actively pushes himself to be as expressive as possible with his facial muscles. The end result is that he makes very strange, whacked-out expressions with huge smiles at moments where it's not appropriate. He eventually gets more natural at it and it lends him a significant advantage in earning people's trust that his eerily-placid peers lack. Shinichi even initially lets his guard down when he sees Miki's friendly, relaxed expression, as he's accustomed to the parasytes being stone-faced.
- The Worm That Walks: He is made of several Parasites, with each controlling a particular limb.
- Worthy Opponent: He's impressed by and deeply interested in Shinichi's parasitism. This is possibly because Miki's control over the parasites on his person isn't as refined as Shinichi's relationship with Migi.
Gotou is a Parasite in the organization led by Takeshi Hirokawa. He is in fact one of five parasites within a single body, created originally as an experiment by Tamura Reiko. He can control all five of the parasites in his host body.
- Achilles' Heel: Reiko states that even though he's tougher than the usual parasite, he's still just as fragile as the others. Shinichi figures it out in the nick of time.
- Affably Evil: While he's not as chatty as Miki, he's a reasonably polite dude who happens to eat people and loves fighting and killing, and will freely compliment a Worthy Opponent.
- Alas, Poor Villain: As Shinichi stands over Gotou's mangled body as it attempts to slowly reform itself, he says he understands that parasites are just creatures trying to find their place, like anyone else and apologizes before killing him for good.
- Beard of Evil: In the movie adaptation.
- Blood Knight: "My only purpose is to fight."
- Combat Compliment:
- When Migi and Shinichi tag-team him with a flaming spear and multiple slicing attacks and nearly kill him, he considers it "very impressive."
- He gives this to Shinichi after the latter stabs him with the metal rod since it was the first time that any human had managed to injure him to any extent. Though in the same breath he also says that he can't allow any human that injures him to live... fortunately, the combination of Migi and the toxins on the rod save Shinichi.
- Comic-Book Fantasy Casting: Maybe, in the manga he looks uncannily like Christian Bale in the movie, American Psycho, despite the fact that the manga came first.
- The Dragon: To Hirokawa, as the most powerful parasite in his organization and the one used whenever Hirokawa needs to eliminate high-level threats.
- Dragon Their Feet: Continues to act after Hirokawa is killed, pursuing Shinichi and becoming the instigator of the work's final conflict.
- The Dreaded: This guy scares Uragami on sight. Later, Shinichi is so terrified of this guy's arrival that he is literally scared out of his mind; he's shivering in fright and lashing out at people like a cornered rat. All from just seeing what Gotou can do.
- Hoist by His Own Petard: Uniting with Migi was a dumb move in retrospect, because while Migi was quite willing to sleep inside Gotou and be controlled, when Migi had a reason to reassert its self and consciousness due to Gotou being poisoned, it immediately sided with Shinichi and tore his guts out. He might have been able to deal with the poison if not for that.
- Impaled with Extreme Prejudice: Shinichi stabs him through the chest with an infected pipe, leading to his body breaking down.
- Leader Forms the Head: Only Gotou, along with Miki, may lead all five parasites, and thus act as leader by being the head - though only Gotou himself can unify them to fight together as one.
- Lightning Bruiser: Moves faster than human reflexes can track, strong enough to shatter concrete with ease, and largely impervious to bullets even if you can get a lucky shot in.
- Meaningful Name: The name "Gotou" is a pun, since the first kanji (後) is synonymous with the kanji for the Japanese number "five" (五 go) - symbolising his ability to control all five parasites within his host body.
- More Teeth than the Osmond Family: In his true form.
- Not So Stoic: After the police raid he becomes very fixated on killing Shinichi, swapping out his former calm demeanour for a much more unhinged one as he hunts the protagonist.
- Obliviously Evil: While he's sentient, he's even more detached from the concept of morality than other parasites. Fighting and killing is just what he does.
- One-Winged Angel:
- His true form in the manga and anime appears much less human and he actually likes to stay in that form as long as there are no people around.
- Averted in the movie adaptation, although his true form is slightly revealed at his demise.
- Purple Is Powerful: The second kanji of Gotou's name, (藤) means "Wisteria/purple" in Japanese - fitting given his status as arguably the most powerful being in the series.
- Red Oni, Blue Oni: In contrast to the talkative and almost playful Miki, Gotou is near-emotionless and handles their assignments professionally and without distraction.
- Run or Die: Effectively what Shinichi and Migi's strategy whenever fighting him boils down to.
- Super Speed: Each of his limbs is a Parasite. Combined with Gotou's reflexes and control, this allows him to run, jumps, and strike faster than the eye can follow. His legs can also reconfigure themselves further, allowing him to keep pace with a speeding truck.
- Super Toughness: His Parasite limbs can extend into/across the rest of his body, reinforcing it to survive the stress of his movements and deflect small arms fire. This protection is limited due to the finite mass of Parasite cells, so parts of his body remain unarmored. This proves to be his downfall when Shinichi manages to spot and stab one of these weak spots.
- The Stoic: Is completely unfazed when the military storms city hall, calmly observing the soldiers exterminating the parasites. When faced with five soldiers pointing their shotguns at him, he nonchalantly turns around and tells them to follow him to a large room, explaining that they'll "have more room this way."
- Ultimate Life Form: He refers to himself as a "pure, feral lifeform", and is far and away the strongest of his species - who as Parasites, naturally rank above humans on the food chain.
- Villainous Breakdown: After being stabbed by Shinichi with a toxic steel pipe, his body begins breaking down and he mentally turns into a savage beast with the fury of a rabid animal.
- Wicked Cultured: When not killing anything that gets in his way, or feeding, he's fine with playing Chopin's Nocturne Op.9 No.2 on the piano in his spare time.
- The Worm That Walks: He is made of several Parasites, with each controlling a particular limb.