Post a psychotic animê character and what is that makes them insane

Genocider Syo.
She's a serial killer who "only kills men who turn her on". She's also another personality of a girl named Touko Fukawa, who's got her own problems even without Syo.

Shion Sonozaki from Higurashi no Naku Koro ni.
[SPOILERS]
Shion is the hidden twin sister of Mion Sonozaki. In one of the many worlds that Rika went through in Higurashi, Shion fell in amor with a boy named Satoshi. But due to certain circumstances, Satoshi killed his own aunt and disappeared. This, combined with a disease Shion had caught, eventually caused her to go insane. She posed as her twin sister Mion and then murdered her grandmother, locked up her own twin before murdering her, murdered Satoshi's little sister, lured one of her best friends to her house in order to kill her (but the girl committed suicide in her house) tortured and killed her current crush, all while demanding that they bring Satoshi back, insisting that it was their fault. She also suffered from delusions of Satoshi talking to her. She later tripped off her balcony and died a bloody death.

. . . . <3

Miyo Takano from Higurashi no Naku Koro Ni.
When she was a child, her parents passed away, leaving her to an orphanage where she was heavily abused. Later on she was taken away from the orphanage por a man her father had recommended, taking the man's name and calling him her "grandfather". She was ever grateful and, of course, saw the man as a savior for being the one to take her away from that place and to show her kindness. However, even if she couldn't see it, this man was just as bad as the people who abused her at that orphanage, if not worse. Yes, maybe so. It can be argued that what he put her through was worse than physical abuse. There's mais to their relationship than meets the eye. It goes beyond now happy-go-lucky girl who's interested in her "grandfather"'s studies. If you haven't seen Higurashi, you won't know what I'm speaking of when I mention what her father obsessively researched, the root of the "Hinamizawa Syndrome", the entity of 'Oyashiro-sama', something that was later seen as a type of god. Her adopted grandfather devoted his life to this research, but alas, everyone he came to with whom he shared his ideas stepped on him and ridiculed him, and Takano witnessed it all.

Take a moment to imagine the impact this will have on Takano, a little girl, seeing the man who rescued her from the clutches of abuse and mockery being treated much the same way for his own pride and joy. She's going to want to do something about it, but in her position, she can't do a thing. por this point, there was nowhere for her to find comfort or relief.

What's the worst of this is that her "grandfather" starting using her as his own tool to carry on his research, and when she was still a growing woman he committed suicide and left her a note about it. Not only did her childhood lack the support that she needed but after he had given up on life he forced his obsessions on her. He was a terrible person and thanks to this, she became obsessive about "carrying on his will" because she still couldn't see that he was never any knight in shining armor. Unfortunately, she was treated with just as little respect upon presenting his research and making her own proposals, and she, of course, wanted revenge, but as soon as she gained power, she had already snapped from her traumatic experiences... Uh-oh...

She's my favorito Higurashi character.

Nui Harime from Kill La Kill.

The thing that makes her insane is the fact that she almost always has this 'cute smile' when she says and does something sadistic.

((*SPOILER* She even had it when she drew the scissor blad in Isshin's guts ****))

And when she gets insane..oh god it's scary ;3;

Madara uchiha from naruto shipudden this guy is insane because he enjoy fighting so much and enjoy getting beat up and enjoy destroying

So much characters to choose from :p. Gasai Yuno from Future Diaries. One moment she seems normal the seguinte she's crazy. She's one of my favorito animê characters. She's in amor wit a guy named Yuuki and gets jealous easily and kills anyone who tries to harm him.

Kousuke Kira. From "Btooom!" Age: 14. He is just super cute/adorable! However, that is how he is on the outside. On the inside he is an insane child, very psychotic, sadistic. He views life as a game. He killed his own father...but there are reasons that are totally acceptable..to an extent. He loves to kill things. He killed then raped 3 women. He was heavily abused when he was younger, and still is to this dia (well in the animê atleast). He was abused sexually, physically, verbally, emotionally.

Kurumi Tokisaki From encontro, data A Live.She's A Spirit From Another Dimension That Is Obsessed With Traveling Back In Time To Kill A Certain Person And She Is Willing To Literally Do Anything To Achieve Her Goal Such As Devouring The Main Protagonist In Order To Absorb His Power.
She Also Killed A Bunch Of People Along The Way And She Is Especially Cruel Toward Those Who Abuse animais !!!!

Aria from Akame Ga Kill!
She and her parents lured people from the countryside and tortured them until they've died.
She snaps when Tatsumi's dying friend Ieyasu rats her out.