Anime villains don’t always stay villainous. Actually, there are plenty of anime villains who turned good. In series like Naruto and Yu-Gi-Oh! this happens to nearly every villain, while other anime use the trope more sparingly. Sometimes it’s heartfelt, and sometimes it’s kind of hamfisted, and it happens for a lot of different reasons.
In some cases, a change of heart occurs when an intelligent villain realizes that their former behavior is no longer in their best interest. In other cases, a villain with good intentions finally gets the opportunity to be the good guy they’ve always been on the inside. Maybe a villain who was really into the whole evil thing realizes the error of their ways after a showdown with the protagonist. Maybe they begrudgingly join the good guys, but their old personality keeps creeping in. No matter the reason, characters who make the switch from villain to good guy can be fascinating.
Vegeta of the Dragon Ball Universe is probably the most famous example of a villain joining the good guys. When Vegeta first appears, he’s a vicious murderer who wants nothing more than to defeat Goku, known to Vegeta by his Saiyan name, Kakarot. After being forced to work with Goku and his friends toward their common goal of defeating Frieza, Vegeta finds himself protecting his former enemies, and being protected in return. When he gets hurt and is forced to stay on Earth longer than he meant to, he starts getting used to the people there, and even growing attached to them.
It takes several relapses into his old ways to fully change, but eventually he does become a valued and trusted ally to Goku and his friends.
In Naruto, most villains eventually realize the error of their ways. However, most of them perish before they get a chance to join the good guys. Gaara is one of the exceptions.
When Gaara first appears, he’s hellbent on destroying as many people as he possibly can, referring to them as prey. This is a trauma reaction – like Naruto, he was vilified by his people for having a monster sealed inside of his body, but unlike Naruto, he was attacked by his own family. His father and uncle literally tried to murder him repeatedly. After a protracted fight with Team 7, Naruto and Gaara have a heart to heart talk about their mutual feelings of isolation and pain, and this convinces Gaara to stop hurting people and dedicate himself to protecting them, instead.
Gajeel Redfox of Fairy Tail starts off as a member of the Phantom Lord Guild, one of the most powerful guilds around. While there’s naturally a lot of infighting between the guilds of Fiore, the Phantom Lord Guild takes the conflict a step too far by attacking members of the Fairy Tail Guild and hanging them from a tree.
When the group eventually disbands, Gajeel is at a loss for what to do next. Despite his direct involvement with the attack on Fairy Tail, the guild’s leader Makarov invites Gajeel to join them. While he doesn’t forgive Gajeel for what he’s done, he also wants to give Gajeel purpose and companionship. Gajeel ends up becomng an indispensable member of the guild.
Yu Yu Hakusho features the murderous Hiei, who dedicated his childhood to various killing sprees. He had to join the Spirit Detectives as a condition of his parole, and he was pretty surly about it until they took on a mission to rescue his twin sister Yukina, whose relation to him had been kept a secret. Despite not being being forced to accompany them this time, Hiei still tags along, making up excuses for why he’s interested the whole time.
Scar is probably one of the most well-developed characters in Fullmetal Alchemist: Brotherhood. He starts off as a villain who targets State Alchemists. Without context, this makes him seem like a monster – with context, it gets more complicated. State Alchemists nearly wiped out his people, the Ishvalans, and destroyed their homeland. Despite belonging to a religion that preaches peace, Scar considers genocide to be a worthy reason for revenge.
His rage leads him to destroy people who were trying to help him, including the Rockbells, who were Amestrian doctors attempting to treat his wounds. When he’s confronted with the Rockbell’s daughter Winry, who hates him for murdering her parents, but is still willing to help him because that’s what her parents would have wanted, he must take stock of the impact of his revenge. As the series progresses, he puts his justified feelings aside to ally with Al, Ed, and others who are working toward the same thing he is – peace.
Like a lot of characters who start off as villains before migrating over to the good guys, Crona of Soul Eater never actually wanted to do anything villainous – they were forced to become a killer by their abusive mother, Medusa Gorgon. Said abuse made it just about impossible for Crona to go against their mother in any way, so for a long time, they simply obeyed while becoming increasingly mentally unstable.
Eventually, Crona meets Maka, and starts feeling wanted to protect her instead of attack her. This eventually leads to recognizing their mother as abusive, realizing that they don’t need her approval and deciding to try to help thwart their evil plans.
When viewers first meet Nishio Nishiki of Tokyo Ghoul, he’s not exactly nice. He immediately decides that Ken Kaneki is untrustworthy, and as a result he harasses him and even tries to fight him to the death. After Kaneki helps him rescue his kidnapped girlfriend, he changes his mind about him, and joins Anteiku, a group of ghouls dedicated to acquiring their human flesh in an ethical manner.
Ken Ichijouji starts off as the Digimon Emperor, the main villain of Digimon Adventure 02. He forces Digimon to do his bidding, and generally creates chaos in the Digital World. The thing is, Ken doesn’t realize that the Digital World is a real place with real consequences – he thinks he’s playing a video game, and he’s chosen the villain route in order to cope with the death of his older brother – also because a river told him to, but that’s the less compelling explanation that the series offers.
After he realizes that his actions actually have did consequences (and spends some time holed up in his room scaring his mom) he ends up joining the other Digi Destined in their quest to save the Digital World from bigger, badder, digital threats.
Kyōka Izumi of Bungou Stray Dogs never wanted to be a bad guy, but her ability, called Demon Snow, left her no choice. Her ability started causing chaos when she was just a little girl – in order to defend herself from an assassin manipulating her parent’s bodies, she ended the life of her own parents. Later, she joined the Port Mafia and took out over 30 people in their name.
Atsushi notices her reluctance, and feel empathy for her – she’s not in control of her abilities, but neither is he when he turns into the were tiger. Despite the protests of the Agency, he rescues her from the Port Mafia. The Agency eventually comes around, and helps shield her from the police, rehabilitate her, and eventually give her work to do on their behalf.
Viral of Tengen Toppa Gurren Lagann starts off as a surface-dwelling enemy of Team Dai-Gurren. As a member of the Human Execution Squad, his goal is pretty self-explanatory. He despises humans, calling them “naked apes”, and is more than happy to help get rid of him. Eventually, a combination of actually interacting with humans on a personal level, being treated disrespectfully by his own comrades, and realizing that attacking humans is not, in his view, honorable, he does and about-face, and ends up joining Kamina and company.
Accelerator of A Certain Magical Index is the most powerful psychic in Academy City. He’s sadistic, aggressive, and he demonstrates this by joining an experiment designed to create a psychic even more powerful than himself. In this experiment, he has to murder 20,000 clones.
The thing about Accelerator is that despite his cruel exterior, he actually has good intentions. He isn’t motivated by a desire for power – he wants to be unapproachable, so that no one will be hurt by challenging him – which will happen the instant he shows weakness, despite the terrifying nature of his ability, which makes him immune to bombs and allows him to literally change the direction of people’s blood. After finally being defeated, he becomes sort of an anti-hero, before eventually becoming a protagonist – a good guy – in his own right.
Teruki Hanazawa starts off as an arrogant pre-teen who uses his psychic powers to gain popularity and power in his middle school. Said power involves control over multiple gangs. When the protagonist of Mob Psycho 100, the titular Mob, is tasked at taking him down, the two of them have a battle so dramatic that viewers are shocked that Teruki leaves the fight with only damage to his hair.
Through their fight, Teruki realizes that he isn’t the only person out there with psychic powers, and in fact he isn’t even the strongest person with psychic powers. His battle with Mob humbles him, and makes him want to be Mob’s friend. When Mob has to go save his brother from kidnappers, Teruki is right there to help him out.
Chlammy Zell of No Game No Life starts off with zero confidence in the abilities of the Imanity, her world’s name for the human race. This perception have something to do with her experience as a slave to an elf family, and her own relative powerlessness in the face of her situation.
At first, she’s vigorously against Sora’s attempts to conquer Disboard. In this universe, conquering is a reasonable and non-villainous thing to do, and is in fact the goal of all civilizations. It’s not that Chlammy is trying to stop Sora from doing something wrong, she’s impeding his progress and acting in a villain-like role out of fear.
When she eventually agrees to help Sora, it’s because he and his sister Shiro prove to her that yes, humans are actually extremely powerful, and yes, they are more than capable of taking on other species with magical abilities.
Princess Tutu’s Rue Kuroha, also known as Princess Kraehe, is the daughter of a raven king disguised as a human, whose mission is to make Prince Mytho fall in love with her. While she’s doing this for fairly innocent reasons – she’s actually in love with Mytho – the Raven is using her to kidnap and destroy Mytho. When Rue discovers the Raven actually kidnapped her as a child, and is not her real father, she joins Fakir and Duck in their effort to save Mytho and defeat the Raven instead.
Every Yu-Gi-Oh! series utilizes this trope multiple times, so let’s focus on a lesser-known example. Jaeger starts off as Rex Godwin’s lackey in Yu-Gi-Oh 5D’s. He goes along with all of Godwin’s evil plans, harasses his kidnap victim Jack Atlas, and is just generally an unpleasant little clown monster. Why does he end up joining the good guys? Because he realizes he has something in common with them.
Jaeger grew up so poor that eating cup noodles was a special treat. Until he started working for Rex Godwin and earning a good salary, his whole family was living in poverty. While he already knew that Jack Atlas had grown up in poverty (and in fact looked down on him for his specific brand of poverty) he eventually bonded with her over their mutual nostalgia for cup ramen, and from there, their impoverished childhoods. After that, Jaeger is willing to help Team 5D’s with whatever they need – as long as it doesn’t involve too much risk to his personal safety.