Matsuura Youji
Youji is Yuu's father whom Yuu believes is not his biological father. Youji divorces Chiyako and marries Rumi. He is a very mellow guy who is very good at math. Although he is very mellow, he still cares deeply for Yuu. His concern for him is very evident in the way that he reacts to Yuu in the Marmalade Boy movie. He is, like the rest of the parents, funny but irresponsible.