Yu-chan is a cheerful female ghost character from the Puyo Puyo series of games. From Puyo Puyo Fever 2 on, she is accompanied with her younger brother, Rei-kun. Yuu makes puns and is constantly silly. Her voice is also loud and, to some, obnoxious.
It is said that she would not be as cheerful if she were still alive. This may suggest that she had a difficult life.