Identity Amnesia in Anime and Manga.
- Tsukasa, the lead character of .hack//SIGN, begins the show with this, with the added bonus of being stuck inside an MMO where he can feel everything. The adult friends he (eventually) makes do what they can outside the game to learn his identity. Parts of his memory come back in pieces as the show goes on such as his mother's love for black-and-white era western films to a shopping mall he used to go to. But the final revelation (that Bear actually figures out relatively early in the show but Tsukasa initially rejects as impossible) is that Tsukasa was actually a girl in real life and her father abused her for the crime of not being a boy.
- Bokura no Kiseki has a Reincarnation variation. Among all the reincarnated characters in the series, Zeze can remember some vague details about his past life but isn't quite sure who he was. (He seems to think he's better off not knowing, though.)
- The protagonist Harusumi pretends to have this, in order to throw off potential enemies of his past life, Veronica.
- Tooya from Ceres, Celestial Legend is the victim of this trope. A plot point, as he is later revealed to be the personification of the highly-coveted hagoromo.
- A Certain Magical Index: Kamijou Touma forgot a lot about who he was when he took a feather of St. George's Sanctuary to the face, and it is irrecoverable. He forgot a lot of people he knew; he forgot why he said people were indebted to him; school; he even forgot what his parents looked like, which is a plot point. While a thank you letter had allowed him to obfuscate competence and convince everyone that he's fine, at least twice he had to gamble that he should have known someone because they dressed weirdly. Eventually, he fesses up to someone about it.
- In Code Geass, after C.C. loses her memory and goes back to her mental state as a slave girl.
- Debatably, this also applies to Lelouch at the start of R2. Since he's forcibly forgotten about his mother, sister, and being Zero, he becomes his civilian-identity mask, a Brilliant, but Lazy student who cuts class to gamble on chess games. He's still dissatisfied with the world as it is, but since he no longer has an outlet, he's got a lot of bottled-up rage.
- Death Note has Light, upon losing his memories, becoming the way he was before getting the Death Note where he is not evil and sympathetic to the people of the world. When he regains his memories, Light reverts back to his evil self.
- Even without his memories he notes that Kira thinks a lot like him, and acts the same way he would act. The evil Light is not so much a different person, as the same person under a different set of circumstances.
- Dragon Ball has this in the protagonist's backstory. When he first landed on Earth, Goku was a typical, Always Chaotic Evil Saiyan, causing his adopted grandfather no end of trouble. One quick tumble down a cliff and landing on his head later, he's the happy-go-lucky protagonist all minions of evil will come to know and fear.
- Elfen Lied uses this as its central plot device: ruthless killer Lucy is hit in the head with a .50 caliber bulletnote and becomes a very child-like girl that can only say "Nyu." However, another blow to the head reverts her back to Lucy, often resulting in at least one person getting themselves killed before the effect returns.
- In the Eureka SeveN movie ending, it is widely believed that when Eureka offered up her memories to Image, she lost all her memories and even basic fundamental knowledge like language (she became unable to speak any language, only making noises). Thus in her case, it is 100% memory wipe, and poor Renton has to live with this fact.
- Golgo 13: In the anime series, Duke Togo has a loss of memory after a bomb explosion, and is aided by the requisite beautiful female bystander. Being The Determinator, even without knowing he's a Professional Killer at first, Togo gathers enough information and fragments of memory to make it to the kill zone he's selected, but the question remains: who was he meant to kill among the people assembled in the kill zone? Togo fires his gun in the air, and the hail of bullets from the bodyguards somehow restores his memories. Then he's faced with killing the woman who helped him, as he must Leave No Witnesses. A stray bullet however takes care of that problem.
- In Granblue Fantasy The Animation, Ferry has no memories of her past whatsoever. It's later revealed that she used to be a fairly ordinary Erune girl who inadvertently became immortal and had her memories stolen when she got mixed up in an evil scientist's scheme to gain immortality. When she finally remembers, her memories merely confirm what she had already pieced together through various clues. What she didn't expect however was the painful memory of saying goodbye to her beloved little sister, who is long gone by the time of the story.
- In Jin, the title character uses this as a cover story for the samurai family he lives with to avoid explaining that he's actually from the future. Unfortunately for him, they are eager to help him search for his identity and after a few weeks, he ends up confessing the truth.
- JoJo's Bizarre Adventure: The protagonist of Part 8, Josuke, is discovered half-buried in the dirt without any memories. Troubled by the fact that he doesn't know who he is, he is driven to uncover his past with the help of Yasuho Hirose, the woman who found him. In the process, he is quickly caught up in a life-threatening conspiracy involving rock humans and a miraculous fruit. Turns out he's an entirely new being, the result of a Fusion Dance between Yoshikage Kira and Josefumi Kujo.
- In K, at first Shiro seems like he really is an Ordinary High-School Student, not the Colorless King who was caught on video murdering a Red Clansman, inciting the Red Clan to seek revenge. But halfway through season 1, things start to indicate that Shiro's memories are actually false. He is without any knowledge of who he is from them until episode 11 when he regains his memory — he is another king, forcibly body-swapped with the Colorless King.
- This happens before the series starts in Loveless. Ritsuka has amnesia and a different personality when it starts. The question of who he was hangs over the series but lessens as he gains friends.
- In Magical Project S, Misao Amano's alter ego Pixy Misa likes to torment the main cast with her magical powers. When Misao reverts to her normal self she doesn't remember any of what she did while transformed.
- Maze suffers from this at the start of Maze Megaburst Space; the only thing about her identity she remembers is the name Maze.
- In Mobile Suit Gundam 00, Soma Peries experienced a rather complicated version of this. She was originally Marie Parfacy, a kind-hearted girl who was a friend of Allelujah Haptism during their childhood until she was implanted with the Soma Peries personality. After the persona was implanted, she lost her memories as Marie and became a ruthless and fearless antagonist of the Human Reform League in Season 1 and then later, A-LAWS in Season 2. Thanks to Allelujah, she regained her memories and returned to her former self and switched allegiances to Celestial Being later in Season 2. Both personalities coexisted until Sergei Smirnov (her commander whom she views as a father figure throughout Season 1) was killed which led to Marie reverting back to Soma. After the final battle, Marie's personality returned and has remained dominant ever since. The Soma persona only resurfaces for combat as Marie doesn't have the stomach for war.
- Monster (1994) has Johan's good-hearted twin sister Nina Fortner, who can't remember that she's Anna Liebert after he forced her to shoot him in the head.
- Averted in Negima! Magister Negi Magi. Although Asuna Kagurazaka is shown to have a drastic shift in personality between her self-induced amnesia at the conclusion of the backstory and the kicking off of the plot (she went from Emotionless Girl to a Hot-Blooded Tsundere), it is shown to have happened over the course of several years, implied to be the consequence of frequent interactions with a Rich Bitch Ojou.
- Noein's resident Ax-Crazy psychopath Atori gets amnesia after nearly dying in combat, and becomes a gentle, if somewhat out of it, young man who enjoys spending time with Miho since she reminds him of his dead little sister Sarah. He does regain his memories later on, but by that point, spending time with Miho and the rest of the group has softened him and reawakened his sense of morality.
- Kirika Yumura of Noir starts out with this. She only knows what her name is due to it being printed on her student ID, and a comment from Chloe towards the end of the series implies that not only is 'Kirika Yumura' not her real name, it was entirely possible that nobody remembered what her real name was.
- Invoked by Usopp in One Piece's filler G8 arc to pull one over the Marines. He pretends that Inspector Shepard, who Robin was impersonating at the time and the Marines mistaken him for a Straw Hat, had suffered an identity amnesia, couldn't recognize him, and thus "believes" he is Shepard and not really their friend "Condoriano".
- Patlabor has one of these with Ota, who doesn't remember anything after a big party and wakes up with a terrible hangover not knowing who he is. Worse, looking at the mayhem around him and his unconscious teammate, he believes himself to be a murderer and runs away from every person who could have explained the jokes his friend played on him (in an attempt to make him avoid unnecessary violence). As you can expect, after a really deep introspection, he completely forgets any lesson he could have learned during his amnesia when he wakes up at the hospital.
- Senri from +Anima gets this. TWICE. Once while he was young and went berserk, (which prompted Crystala to give him his pressed flower book to remember people.) The other time he goes berserk with Husky, Nana, and Cooro there. He can't remember them and tries to attack. He is eventually stopped when Cooro slaps his Eyepatch of Power on.
- Ranma ½:
- A blow to the head during a weird training method involving watermelons changed Kuno from an ineffectual, harmless buffoon with weird (but funny) romantic notions, to a nigh-unbeatable stalker who might have succeeded in forcing himself on female Ranma if she hadn't knocked him back to his senses first.
- In an anime Filler episode, Ranma Saotome gets struck with something that's one part this, one part Loss of Identity after Akane knocks him into the koi pond with a frying pan, causing him to smack his head hard against one of the rocks on the edges. When Ranma regains consciousness, "she" remembers that she is Ranma Saotome and who everyone is... but "her" personality has done a complete 180, turning the gender-bending boy into a parody of an ultra-girly girl.
- Elie, one of the main characters in Rave Master is actually Resha Valentine, who faked her death and put herself into a deep magic-induced sleep to defeat an enemy predicted to appear 50 years in the future. Not that she remembers this thanks to either possibly erasing her own memories as a side effect of her deep sleep or Sieg Hart blowing up the building she was in. When she's introduced she tells Haru that she's actually looking for someone who knows her.
- This is what happened to Seiya's older sister Seika in Saint Seiya.
- In episode 16 of Scrapped Princess, Pacifica gets amnesia after being blasted out of the mobile fortress she was in, and spends most of that episode in town under the assumed name of "Pamela". She spends two more episodes like this, even insisting that her name is "Pamela" when her friends recognize her. She later regains her memory after being captured by Chris and later rescued again by Shannon, at which point she has no memories of her time as "Pamela".
- It's implied that her memories are trying to surface from the time she meets up with her siblings and that she unconsciously suppresses them, as her current life is quite peaceful and idyllic compared to, well, the rest of the show. After the first meeting, Raquel advises that they let her be content for at least a little while.
- This Ugly Yet Beautiful World: Hikari and Akari know nothing about themselves when Takeru and Ryo find them. Justified. They aren't even human, and didn't even have identities to forget.
- In the sequel to Tokyo Ghoul, Haise Sasaki is revealed to be suffering from dissociative amnesia and has a full-blown Freak Out when confronted about his past. He's actually Ken Kaneki, captured by CCG at the finale of the original series and given a new identity after suffering both a complete mental breakdown and massive head trauma.
- Kinme, from Wash It All Away, knows nothing about herself from before two years ago, except that her name is Kinme, which she admits might not even be her real name, and that she's really good at, and enjoys, doing laundry.
- Sakura has this in Zombie Land Saga, even though none of the other zombies do. It is likely justified, though, by the means of her death; massive head trauma from being hit head-on by a speeding truck.
