How much do you know about Undere? This page will teach you everything you need to know.
The Undere (ウンデレ) type refers to a character who says yes to pretty much everything the one they love says. They agree as much as possible to become as close as they can to their love interest.
This word is an abbreviation of Un (ウン) which is a short way Japanese people say Yes and Deredere (デレデレ) which means lovey dovey.
And that should answer the question “What is Undere?” You can find more information on subcultures and terms just like this in my growing Otaku Encyclopedia, including all other -Dere types!