A yandere is a character whose romantic devotion turns obsessive and unstable, expressed as possessiveness that can escalate to menace or violence in fiction. The name blends yanderu (to be mentally ill) with dere (lovestruck).
The yandere is the extreme end of the -dere family, and the word is built differently: yan comes from yanderu, to be mentally ill, rather than from a manner like coolness or silence. The pattern it names is devotion without a governor, affection that interprets rivals as threats and separation as catastrophe, played variously as dark comedy, horror, or tragedy.
The archetype crystallized in the 2000s through games and anime that used obsessive devotion as a plot engine, and it remains a live one because it dramatizes a real story question: what love looks like when it stops recognizing the beloved as a separate person. Serious works treat the type as damage; shallow ones treat it as spice, and fans argue the handling case by case.
This glossary defines the term as a fiction trope, which is its actual usage in criticism and fandom. It names a pattern in stories, not a diagnosis of people, and it appears here for the same reason the rest of the family does: viewers use the word, so the word gets a precise meaning.
In use"Sweet devotion curdling into surveillance and threats when the beloved talks to anyone else is the yandere turn."