Post an Anime character that have dual personality :3

Stein!! :D

Jun Yamamoto from Special A

Kotori Itsuka from datum A Live.

Her personality changes depending on what color ribbon she's wearing in her hair. When she wears white ribbons, she's a weak little sister. When she wears black ribbons, she's a strong leader. And when she's in her "Spirit form" for too long, she develops a third personality that makes her a ruthless killing machine.

In short, Kotori's a moe little sister, tsundere commander, and psychotic killer.

Ukyo from Amnesia

Lucy from elfen lied

Iori from Kokoro Connect.

Shinomiya Natsuki / Satsuki. x3

Usami Hani from Sket Dance

Hatasuharu Sohma from Fruits Basket.

Moka from rosario vampire!! :)

Hanekawa Tsubasa :)!

Father AbleNightroad from Trinity Blood.

(sort of) Alice from PandoraHearts

Momoka from Keroro Gunsou

Kawamura Takashi from Prince of Tennis....He is a soft-spoken person off the court, very gentle and shy, though still outspoken and stubborn when he takes a decision. However, he becomes extremely aggressive and loud once he grabs his racket, oder any racket.
This change in his personality is marked Von him shouting "Burning!!!" "Great!!!" "Baby!" His personality along with these Schlagwörter when he holds a racket is most likely just for comic relief, but his personality change does have a large impact on his skills. While in his Burning Mode, he has a tendency to speak in English and to call people, mainly underclassmen, monkeys.

Ichigo Kurosaki (Bleach)

ichigo has 2 personalities...............
1 his own.& the other a hollow's.............he he he hehe

Train Heartnet from Black Cat.

1. The Mehr self-keeping, vengeful, and serious side of him.

2. The complaining, childish, annoying, and carefree side of him that was sprung on us Von surprise. It made me like his character a lot less -_-