Yandere

Yandere is a portmanteau of two Japanese words yanderu, meaning to be sick, and deredere, love struck. The term describes someone who has been driven to insanity by extreme obsession or love, thus resulting in abnormal behavior if not violence.

A classic example of a yandere is Yuno Gasai, from the series Future Diary, who is prone to kill anyone who may interfere with her obsessive passion for the series' protagonist, Yukiteru Amano.

Personality
A yandere has tendency to threaten anyone who is close to the person they are attracted to. They like to be manipulative and want to keep their love interest only for themselves. When interacting with their love interest, they don't always reveal their true personality and the other person sometimes discovers it when the yandere lets their guard down. However, they can be also more openly yandere and not hide their way of thinking or their actions.

Contemporary Usage
This term can relate to a character in anime or manga to describe their personality, but can also be used towards real-life people.

Notable Examples

 * Yuno Gasai from Future Diary
 * Minatsuki Takami from Deadman Wonderland
 * Anna Nishikinomiya from Shimoneta
 * Kaede from Elfen Lied
 * Nina Einstein from Code Geass