源 優子

Specialities: studying, sports in general
Weakness: music
Hobby: gaming

Kouji's childhood friend and the school student president. She is also Kouji's ex-girlfriend. Her parents divorced when she was young, and she was taken custody of and raised by her mother who runs a beauty clinic. Strict about regulations and promises, but otherwise a very laid-back personality. For better or worse, in some respects she is inattentive and sloppy with budgeting. She is a big sister figure in that she looks after her juniors well and treats men and her seniors with impartiality, but she has gaming as her hobby and is a super gamer girl to the point that she has gaming system boards at her home and can even create cable harnesses herself.