BANK-008 My childhood friend is a super cute tomboy with a short haircut, her name is Hirata Mana.

Mana looks like a boy but is a cute and handsome girl. She has only had one male experience, and she consults her childhood friend Kenji, who acts like an older brother, about love and sex. Kenji gives serious advice but gets too enthusiastic and starts practical training. The two take it seriously at first, but gradually start to feel strange, and the situation escalates. The young pair end up being driven by instinct rather than reason.