Aiba Mutsumi

She is Chihiro's blood sister and Tooru's aunt. She is a career woman working for a general trading company.

In contrast to her sister Chihiro, Toru has a strong, forceful personality. However, in front of her family, she is sloppy and unable to do any housework. She lives her life with her work, and when she misses the last train, she comes to stay at Tooru's room.

She is often the subject of obscene glances from men both inside and outside the company because of her glamorous body line, which can be seen even through her suit. This has made Mutsumi dislike men, and she is an unmarried elderly virgin.

The only exception is her nephew Tooru, who is a virgin, and because of this, Mutsumi will get dressed in her underwear even in front of him, or get drunk and sleep on his futon without his permission.