What is onii chan?

"Onii-chan" (お兄ちゃん) is a Japanese term that means "older brother" and is often used by younger siblings to address their older brothers in a familial and affectionate manner. It is a casual and informal version of "onii-san" (お兄さん), which is more polite.

In anime and manga culture, "onii-chan" is frequently used by characters, becoming a trope in which younger sisters or female characters use it to address an older male character, whether they are related or not, often to show familiarity and affection. This can sometimes be extended beyond direct siblings to close family friends or in metaphorical sibling relationships.

The term has also made its way into popular culture outside Japan, where it is often recognized by fans of anime and manga. It's become emblematic of certain character dynamics in Japanese media and is often used both sincerely and playfully in a variety of contexts.