Yandere

Yandere is a Japanese term used to refer a person who is sweet and kind at first glance, only to reveal their unstable, obsessive, and violent side when it comes to their love (crush).

The term is a portmanteau of the words yanderu (病んでる), meaning (mentally or emotionally) ill, and deredere (でれでれ, "lovey dovey"), meaning to show genuinely strong romantic affection.

Overview
Yanderes are people who suffer from personality disorder and can easily become violent and extremely dangerous similar to yangires where in this case, being motivated by their obsessive love to someone whom they have a crush with. He/she would go to extreme lengths to rid of anyone who potentially about to take away and/or harm his/her crush, which includes murdering their rival. A yandere usually puts up a sweet and kind facade to conceal his/her violent side and giving others a false sense of security as long as they not enciting her wrath. Although known yandere characters mostly female, male examples do exist.

The term yandere itself gained a considerable popularity in the light of the airing of the infamous last episode of School Days, and would later brought again following the real-life murder attempt made by 21-year-old woman Yuka Takaoka on May 23rd, 2019, in which Yuka's confession over her crime (in which she said, "Since I loved him so much, I just couldn’t help it. After killing [him], I, too, wanted to die.") led many likened Takaoka's behavior to that of a yandere.

Female Examples

 * Yuno Gasai from Mirai Nikki.
 * Nurse Harris from The Labours of Hercules

Male Examples

 * Kyouji Shinkawa from Sword Art Online II
 * The Protagonist from The Horror of Our Love