Chibi

Chibi is everyday Japanese for something short or small, and it has been used about small children, small animals and, rudely, short adults. Fandom outside Japan repurposed it to name the art style: an oversized head on a two-head-tall body, stubby arms, feet reduced to blobs. Inside the Japanese industry the style is more often called super deformed, or SD, which sounds like an insult and is not.

The style is a tone switch, not a separate cast. A series will drop into chibi for one panel when a character sulks, panics or says something petty, then snap back to full proportions for the next line. Because the mode is understood, an artist can play a joke and a serious beat back to back without either undercutting the other. Gag series simply live there permanently.

It is also a merchandising engine. Small proportions survive being cast in vinyl at three inches tall, printed on a sticker, or squeezed into an app icon, where realistic proportions turn to mud. Sailor Moon named a character after it outright. Chibiusa is chibi plus Usagi, roughly little Usagi, and the pun is the whole naming logic.