Multiple personalities add further depth to an anime character's development. Contrary to popular belief, characters with multiple personalities are not all villainous.
Having multiple personalities may be a response to childhood trauma or a way to make them appear more complex and multi-faceted. Or it could showcase different sides of them to the audience. It's also possible that the mangaka wanted to add a unique spin to their character to propel the story in a certain direction. No matter the reason, multiple personalities in an anime character may serve as a potential explanation for their actions.
10 Hatsuharu - From A Peaceful Cow To A Raging Bull (Fruits Basket)
Like his Ox Zodiac, Hatsuharu is patient and laidback, sometimes to a fault. He goes at his own pace with a straight face, following whatever path catches his attention. But he remains stubborn and caring when it comes to his family and friends.
However, there are times when "Black Haru" emerges at the most random of times. This Haru is loud, violent, and aggressive, ready to start a fight with the first person he sees. Usually, it's Kyo. Black Haru also has a perverted side, which often gets him scolded by Yuki.
9 Sensui Uses His Personalities To Push His Goals Further (Yu Yu Hakusho)
Yu Yu Hakusho has a way of portraying its antagonists as complex, multi-faceted individuals as the series progresses. One of its most fascinating villains has to be Shinobu Sensui. As a Spirit Detective, Shinobu upheld a strict sense of justice with very black and white views on humans and demons. His ideals were shattered upon witnessing several demons tortured for the humans' sick pleasure. His disillusion sent him on a murderous rampage and a quest to purge the world of humanity.
Sensui's mind splits into six fragments as a coping mechanism for his now broken ideals. Each piece takes on one aspect of his personality, ranging from the charismatic Minoru to the sadistic Kazuya, tasked to perform a specific duty in his plans. The primary personality, "Shinobu" is meant to be the glue that holds them together.
8 Natsuki And Satsuki Are Like Yin And Yang (Uta no Prince-sama)
ST☆RISH's Natsuki Shinomiya is the gentle giant of the group, immersing himself in anything small and cute. He's airheaded and naive, much to the worry of his childhood friend, Sho.
Natsuki has "Gemini Syndrome," where his other personality, Satsuki, emerges when someone removes his glasses. Unlike the bubbly and kind-hearted Natsuki, Satsuki is aloof with a terrible temper. According to Sho, he's hospitalized anyone who crosses him. When Natsuki's glasses are put back on, he doesn't remember what he's done as Satsuki.
7 Zenitsu Is a Crybaby By Day And Thunder Breather By Night (Demon Slayer)
Throughout most of Demon Slayer, Zenitsu is seen as a coward with a lot of pent-up anxieties. However, he's not as much of a crybaby as people think he is.
When he's not fearing for his life or vying for Nezuko's affection, Zenitsu is more level-headed than Tanjiro and Inosuke. He's also more worldly than the other two, who lived in the mountains, as can be seen from his knowledge of trains. He has a more serious side when he's unconscious, bringing out his true strength. He earns him a spot as a Demon Slayer, even though he lives in constant fear of being killed.
6 Suikotsu, A Kind-Hearted Doctor With A Fear Of Blood (InuYasha)
One may say that Suikotsu is the anime version of Dr. Jekyll and Mr. Hyde, a gentle physician who cares for the village orphans but also a sadistic and bloodthirsty mercenary. Despite his profession, he has severe hemophobia, which can trigger the mercenary personality to take control.
Suikotsu forgets his murderous tangents when he regains consciousness because he suffers from psychological trauma. He witnessed horrendous amounts of bloodshed and destruction during his travels, which caused his mind to snap and develop this second personality. Regardless, Naraku still takes advantage of the kind doctor, using his evil side to do his bidding.
5 Yogi Goes From Sweet And Childlike To Brutal And Murderous (Karneval)
As a member of Circus, Yogi is a skilled swordsman and friendly mascot character around children. Although immature for his age, Yogi is charismatic and bubbly around anyone he meets. Unless it's around Gareki, then he comes off as more annoying.
However, Yogi has a violent side whenever his allergy patch is removed from his cheek. His hair and eye color change from blonde to silver and purple to red, respectively. In this state, known as "Silver Yogi," he attacks anyone in his path, even his teammates. The reason behind this alter ego remains a mystery.
4 Akashi Commands His Team With An Iron Fist (Kuroko no Basket)
To draw out Taiga's full potential, he and Tetsuya must face the last member of the Generation of Miracles: Seijuro Akashi. Seijuro's presence appears unassuming at first, despite his status as the famed team's captain, but his intimidating aura slowly seeps out. He's calm and collected, running his team like a well-oiled machine, and he carries this demeanor into his high school basketball team.
His second personality is a more twisted, controlling version, manifesting through the omnipotent Emperor Eye. Seijuro's left eye changes from red to orange, and he displays more hubris and a severe "winners only" mentality. He's less tolerant of anyone who looks down on or attempts to defy him; he's able to use his commanding aura to bring an opponent to their feet.
3 Zetsu, Two Halves Of One Man (Naruto)
The two halves of Zetsu still function as one unit, despite having opposite personalities. Each side of his face divides into White and Black Zetsu and can split when necessary. White Zetsu is the playful, talkative right side who befriended Obito after his revival. He appears dim-witted but is obedient and loyal, earning the Akatsuki's trust. He is characterized by a higher-pitched and softer voice in the anime.
Black Zetsu, on the other hand, has a deeper voice and is more serious and sharp-tongued. He's intolerant of nonsense and holds no allegiance to anyone who obstructs Madara's (or more specifically Kaguya's) goal. He, too, is obedient to the Akatsuki and will occasionally disagree with White Zetsu.
2 Twice Struggles With Understanding His Identity (My Hero Academia)
When he's outside of his villain costume and mask, Twice assumes an eccentric and lively persona. He's no stranger to dramatic poses and comedic quips, occasionally making jokes with the other League of Villains members. As soon as he dons his mask, his manic personality takes over.
His different personalities result from a need for connection. Each of these personalities is a "friend" he created to combat his loneliness and feel comfortable in his skin. Joining the League of Villains also helps him cope with his loneliness because the other members accept him and his multiple personalities.
1 Momoka Nishizawa Goes From Sweet To Sadistic On A Dime (Sergeant Frog)
From elaborate plots to straightforward confessions that never seem to go anywhere Momoka Nishizawa will do anything for her beloved crush, Fuyuki. To most people, Momoka is sweet and gentle towards anyone she meets, becoming especially shy around Fuyuki.
But her other personality shows a loud, hot-tempered side that not many people are aware of; her eyes also change shape with the sound of a sharpening sword. Momoka may seem like a "yandere" due to her devotion to Fuyuki, but her split personality stems mainly from her mother, who exhibits the same traits.