Yuu Koito (小糸 侑こいと ゆう Koito Yū? ) is the main protagonist in Bloom Into You. She is a first year high school student who doesn't know what it's like to fall in love. She joins the student council, where she meets Touko Nanami. She lives above the family bookstore, where she occasionally works.

Yuu has brown eyes and hair that in the manga is paradise peach and in the anime is deep peach which she wears in a pair of small ponytails above her neck.