In the anime and manga fandom, including AIBooru, the term tsundere (JP: ツンデレ, from tsuntsun (JP: ツンツン), to turn away in disgust or anger, and deredere (JP: デレデレ), to become affectionate) is used. It depicts a character who is initially cold, temperamental, hotheaded, (and sometimes even hostile) before gradually showing a warmer and friendlier side over time. Their nature are generally more comedic than characters with obsessive love disorder, however this character type can be played more seriously as well.
This tag, specifically, refers to characters displaying this personality via contradicting actions and emotions. The easiest example is offering a valentine's daygift, but telling the recipient something akin to "It's no big deal, I don't care about you, I just had some extra."
Often, this kind of behavior can result in mixed signals.
The general definition of a tsundere is a character who starts out combative towards another character but as they get to know each other, the former changes to a warmer personality and generally staying there. The other types came up as a result of various authors trying to copy it.
