Mitsuba is a supernatural created by Tsukasa from a part of the soul of the original Mitsuba Sasuke. After feeding him the heart of the past 3.School Wonder, Mitsuba became the new 3.Wonder. His abilities include moving through mirrors, observing through a mirror or viewing the past from mirrors within the school grounds. He has to eat supernatural hearts in order to maintain his ghostly body, and Tsukasa is ready to help him with this, even forcibly if necessary.

Mitsuba is having trouble finding his place, but he really wants to have friends and deep inside he envies the living. He usually hangs out on his boundary or in the room of The Broadcasting Club, which includes Sakura, Natsuhiko and Tsukasa, who is often mess with him.

The broadcasting room is the boundary, a small windowless room that is located somewhere under the school. There is a thin layer of water, an old couch under the wall, old furniture and things for broadcasting.