Rivalries and friendships can bring a lot of unexpected twists to any anime series, especially when a trusted character turns around and delivers a stunning betrayal.
Traitors in anime can have a huge impact on their stories, even going as far as taking the entire plotline in new and unforeseen directions. The writers might leave hints and foreshadowings for us, but even so, we often don't realize until their true faces are revealed.
The best anime series employ betrayal plot points in all kinds of ways. Sometimes a good friend is tempted to switch sides. Sometimes the villain plants a mole. Sometimes the situation changes and the enemy-of-my-enemy simply becomes an enemy.
Here are my picks for the worst anime traitors and backstabbers that turned their stories upside down with their betrayals.
Note: It should go without saying that this article will be full of spoilers. Scroll slowly and read at your own risk!
18. Bakuzan (One Punch Man)
In One Punch Man, Bakuzan is a martial artist who got blasted into the sky with a single punch from Charanko (i.e., Saitama in disguise). He felt humiliated after that fight, which understandably led to a growing sense of anger and thirst for power.
In the end, he was driven to the point of eating a monster cell, which turned him into an ally of the monsters and a traitor to the human race.
Though he gained the power to defeat Suiryu, he still never stood a chance against Saitama. A short time of tremendous power amounted to an even worse defeat, which cost him his life.
17. Cain Madhouse (To the Abandoned Sacred Beasts)
The Incarnate Soldier Units were the best fighters of the army, comprised of humans who could turn into monsters and beasts (called Incarnates). Yet, because they were experimental beings, they eventually manifested side effects and could no longer control their own transformations.
Cain Madhouse (a Vampire Incarnate) was a member of the squad led by Hank Henriette (a Werewolf Incarnate). Hank's plan was to kill the Incarnates using Godkiller bullets to prevent further disasters caused by these uncontrollable monsters.
Cain Madhouse went on to betray Hank, taking over the other Incarnates and planning to rule the country using fear and power.
16. The Warriors (Attack on Titan)
In the first season of Attack on Titan, Reiner, Bertholdt, and Annie joined the Survey Corps alongside main characters Eren, Mikasa, Armin, and the rest of the gang. They slept, ate, and endured training together and became full-fledged Titan killers together.
What the group didn't know is that Reiner, Bertholdt, and Annie were secretly Warriors: the Titans responsible for the Titan invasion of Shiganshina District and the fall of Wall Maria.
Annie was eventually caught after she lost to Eren while fighting in their Titan forms, and Reiner and Bertholdt voluntarily revealed their identities to Eren in hopes of turning him to their side.
15. Fujiko Mine (Lupin the Third)
Fujiko Mine is part of Lupin's gang, despite Jigen and Goemon's distrusting and unwelcoming attitudes toward her. Sometimes she's taking part in heists with them, and sometimes she has her own separate jobs that incidentally coincide with the trio's schemes.
Yet, even though the operations are typically team efforts with everyone risking their lives, there are times when she wants all the loot for herself, and that kind of makes her a traitor to the crew.
As if that weren't bad enough, she's usually tricking Lupin with her beauty and taking advantage of his feelings of infatuation towards her to take all the precious stolen items for herself.
14. Gin Ichimaru (Bleach)
At first, Gin Ichimaru was a traitor to Soul Society with Sōsuke Aizen as his leader. He helped Aizen with his Hollowfication experiments and even helped plot Aizen's fake death.
But in the process of conquering Katakura Town, Gin surprisingly stabbed Aizen with his Zanpakuto, then stole the Hōgyoku (which was his true intention from the very start).
Unfortunately, his efforts bore no impact and had no effect on Aizen because the Hōgyoku was already his whether it was in him or not. For his sins, Gin died in the arms of Rangiku.
13. Kaede Kayano (Assassination Classroom)
Fans never suspected that Kaede Kayano could really take on Korosensei by herself. She appeared to be a normal student and interacted with everyone as if she were someone they knew as a friend.
Akari Yukimura (her real name) is the sister of Aguri Yukimura, who was an important person to Korosensei in the past. With her great acting skills, she was able to hide her bloodthirst and trick Korosensei into being comfortable with her. A grave mistake!
The thing is, Akari wasn't a traitor for wanting to kill Korosensei, but for hiding her true identity from everyone. That alone made all her classmates lose their trust in her.
12. Hisoka Morow (Hunter X Hunter)
Hisoka Morow is one of the most mysterious characters in Hunter X Hunter. All we can say about him is that he's good at being a villain and he loves facing strong opponents, which he showed when he allowed Gon and Killua to live so they could grow stronger before he hunted them.
Because of his craving for stronger opponents, Hisoka also betrayed the Phantom Troupe and helped Kurapika by sharing all the information he knew about the gang—simply in exchange for a fight with Chrollo Lucifer, the leader of the Phantom Troupe.
11. Meleoron (Hunter X Hunter)
Meleoron is a chameleon-type Chimera Ant and one of the Squadron leaders of the colony. After witnessing the death of the man who adopted him, he left the colony to avenge his late foster-father and defeat the Chimera Ant King, Meruem.
In his search for vengeance, he encountered the infiltrating Hunters and made contact with Gon, eventually forming an alliance with him and the rest of the Hunters.
Ultimately, Meleoron betrayed his King and chose to side with the humans in their goal to eliminate Meruem. While his switching of allegiances wasn't a huge loss for the Chimera Ants, it ended up being a huge benefit to Gon's team.
10. Squard (One Piece)
Squard is the Captain of the Maelstrom Spider Pirates, who sails under the banner of the Whitebeard Pirates. Prior to this, he led a group that was defeated and killed by the Pirate King, Gol D. Roger.
With Akainu playing a dirty trick on him, Squard was deceived by the truth that Ace was Roger's son, which made him hate Whitebeard for making him tag along with the son of the pirate he hates the most.
He eventually approached Whitebeard at the Moby Dick in the middle of war, leaving the battlefield behind to stab him.
9. Black Zetsu (Naruto Shippuden)
Black Zetsu lived for many years—long enough to deceive the Ashura and Indra incarnates and manipulate Madara Uchiha.
Madara believed that Black Zetsu was a manifestation of his own will, not knowing that Black Zetsu had existed since long ago, just after the sealing of Kaguya Otsutsuki.
Just as Madara casted the Infinite Tsukuyomi, Black Zetsu showed his true colors and attacked Madara from behind, using the abnormal chakra flow to bring Kaguya Otsutsuki back to life.
8. Marshall D. Teach (One Piece)
Marshall D. Teach, now known as Blackbeard, was a former member of the Whitebeard Pirates. He killed Thatch and stole the newly acquired Devil Fruit, which gave him the power of the Yami Yami no Mi and its ability to pull and absorb anything into darkness.
His betrayal of the fleet caused so much trouble for the crew and the rest of the world because of Ace, who wanted to pursue him and was later captured and imprisoned at Impel Down.
Whitebeard persuaded Ace to not go after Blackbeard, but the hard-headed son still boarded a ship to chase the traitor.
7. Ray (The Promised Neverland)
While the orphans were planning to escape Grace Field House's nightmarish circumstances, Norman noticed something unusual in his surroundings and plotted a way to verify his doubts.
Ray, one of the orphans who with them all along, was caught being the spy for Mama Isabella. Luckily for them, Ray was actually a sort of double agent who fed Isabella half-truths.
He was actually planning to sacrifice himself for the sake of the other orphans, but Norman's intricate plan carried him along and allowed him to keep going without having to give up his life.
6. Himiko Toga and Twice (My Hero Academia)
The Himiko Toga and Twice duo brought a lot of twists to My Hero Academia during the Shie Hassaikai Arc. They managed to answer safely to Shin Nemoto's Confession Quirk, dodging the question of whether they were ordered to betray Shie Hassaikai.
In the process of the heroes' infiltration into Hassaikai's base, they provoke Mimic and made him unstable, causing abnormalities in his Quirk manifestation.
They even called reinforcements for the heroes using their Quirks, a perfect and sneaky way to betray the gang without them knowing.
5. Mechamaru (Jujutsu Kasien)
Mechamaru (real name Kokichi Muta) from Kyoto Prefectural Jujutsu High School was revealed to be the traitor in Jujutsu Kaisen who leaked information to Kenjaku's team.
However, he didn't do it out of hatred or revenge. Instead, he made a Binding Vow with Mahito on the conditions that Mahito wouldn't lay a hand on his classmates and that Mahito would heal his deteriorating body through Idle Transfiguration.
Upon reaching the end of the contract—with him acquiring a fully healed body—he intended to defeat the Special Grade Curse with his own powers as it was his plan all along to redeem himself.
Unfortunately, he didn't get a chance to use his newly acquired body as he ended up dead in his battle with Mahito.
4. Uryū Ishida (Bleach)
We all know that Uryū Ishida is the last surviving Quincy in Bleach—at least until Yhwach and the rest of the Quincy army arrive on scene.
Uryū was always by Ichigo's side, starting from when Ichigo became a Substitute Shinigami to their sneaky entry into Soul Society to saving Rukia to their battle with the Fullbringers.
But in The Thousand-Year Blood War, Uryū is seen alongside his fellow Quincies. Not only that, he's destined to become their king after Yhwach! Will he really just throw away their friendship and give his loyalty to the Quincy King?
3. Walter C. Dornez (Hellsing Ultimate)
Walter C. Dornez was once the fine old butler of the Hellsing family, a loyal servant to Integra and the organization. He's a great fighter and hunter—which earned him the nickname "Angel of Death"—and even in old age he still poses a great threat to his enemies.
However, he betrayed Integra and the Hellsing Organization "out of his free will." He willingly became the subject of experiments conducted by the Millennium to get a body capable of fighting the organization's ultimate weapon: his former comrade, Alucard.
Drunk on his new powers, Walter jumped off and faced Alucard in a one-on-one battle but ended up being defeated due to the complications of the vampirization experiment.
2. Kanjuro (One Piece)
Kanjuro is one of the retainers of Oden Kozuki along with Kin'emon and the rest of the Nine Red Scabbards. He stood alongside the Straw Hat Pirates during the Dressrosa Arc and the Zou Arc, and he even faced near-death situations many times with them.
Turns out, Kanjuro was actually a spy planted by Orochi Kurozumi during Oden's reign, long before the current timeline. But what made his revelation so shocking to Kin'emon is that he was there with the Kozuki family during all of their sufferings.
Since he was raised as a performer, Kanjuro easily fooled everyone with his fake smiles and tears, making them feel that he really was one of them. It was all just an act on the stage set by Orochi.
Fortunately, the return of Denjiro—another of Oden's retainers—reversed the aftermath of Kanjuro's plot. Denjiro joining the Ninja-Pirate-Mink-Samurai Alliance gave hope to the broken Scabbards.
1. Sōsuke Aizen (Bleach)
Sōsuke Aizen was once a Captain of Soul Society who led the 5th Division of Soul Reapers. But because of his greed for power and wanting to reach the level of the Soul King, he betrayed his allies and devised a plan that wreaked chaos across Soul Society.
From faking his death to invading Hueco Mundo, from deploying Rukia to the Human World to creating Wonderweiss (an Arrancar capable of sealing Captain Yamamoto's Ryūjin Jakka and its flames), Aizen had a plan and set everything into motion.
He also incorporated his Zanpakuto's Shikai in his plots. His Kyōka Suigetsu really does take after his personality: a blade that deceives and tricks the viewer's senses with total hypnosis.