The heart belongs to family, but the body represents others—a delicate relationship. Spending a week alone with one's stepmother inevitably leads to mistakes. (Kino Nono, Erika VENX-304)

Erika remarries a man a year older than her. With the arrival of her husband's stepson, Tatsuya, the three begin their new family life. Erika and Tatsuya, being close in age, quickly become friends. However, their close relationship makes Tatsuya realize she is a woman. During her husband's week-long business trip, her relationship with her son becomes complicated.