After the death of her mother, the Yokomiya household became a single-parent family. The father worked hard to support his daughter Nanami, while Nanami herself grew up serious and composed, both at school and at home. However, she harbored feelings for her father that went beyond a normal parent-child relationship, and to suppress them, she resorted to daily masturbation for comfort. One day, when her father announced his plans to remarry, her pent-up emotions finally erupted beyond control—.