Childhood friends Asami and Mizuki shared a deep bond despite their age difference. Mizuki, an only child, looked up to the older Asami like an older sister. She had dated guys her age and experienced sex a few times, but it never felt fulfilling. Relationships with men always left her with a sense of discomfort and emptiness. For Mizuki, time spent with Asami was special. Gradually, Mizuki's heart turned toward Asami, leading her into forbidden feelings.