Yandere is a term for a character whose love, admiration, and devotion to their love interest is so strong that it causes them to become mentally unstable. Their love is expressed as an excessive obsession and possessiveness towards their love interest. They become so attached to their love interest that it’s impossible to let go and they may even use violence towards anyone who “threatens” their relationship.

Yangire is someone who snaps and turns into a psychopath – often a murderous psychopath. It’s often associated in anime with female characters who appear cute/innocent but go completely crazy. Yandere characters are motivated through love, a yangire character will not be connected with emotions of love or attraction. Yangire is a combination of the two words yanderu (病んでる), meaning to be sick, and gire (切れ), meaning to cut, slice, or “to snap”. Yangire seems to be a western creation, meant to fill the lack of a popular Japanese term for more traditional psychopath, sociopaths, etc

Tsundere (ツンデレ) is a type of character known for switching between two unmistakable moods: one is cold, hostile, and impolite, while the other is warm, affectionate, and caring. The term “tsundere” is a combination of the Japanese words tsun tsun (ツンツン) an adverb for acting big-headed, haughtily, aloof, and sour. And the word dere dere (デレデレ), an adverb for being flirtatious and in love.