長津田 夕美

Yumi is Chiharu's best friend and classmate as well as Ichio and Seiji. In the top of the best students in the class, Yumi is a very smart girl. Very close to Chiharu, she became extremely worried for her when she learned that Tomoko-senpai had chosen Ichio "the naked man" as a volunteer to help her prepare for the Christmas party. As a good friend, she joins Ichio so that she can keep an eye on him and he doesn't attack his friend Chiharu.

However, while they were cleaning the old school chapel to serve as their operating room, Yumi got her feet tangled and a pile of cardboard began to fall on her when heroically, Ichio used his body as a shield to protect the young girl's beauty. Touched by his chivalrous action, Yumi decided to join the group as a volunteer in order to pay her debt.

Yumi is a cold girl, who doesn't show her emotions as easily as other people. However, she has an S side that expresses itself willingly when it comes to annoying her friends.

She is the first girl to show more than friendly interest in Ichio.