Ayaka, the older sister, watches over her younger sister with strength and kindness. Rei, the younger sister, adores and longs for her sister. The feelings between the two, bound by a strong bond, turn into love... Every day, Rei relieves his growing feelings for his sister by masturbating. One day, when Ayaka comes home drunk, Rei rapes her at night. A few days later, Rei gives Ayaka advice about her broken heart, but decides to confess his feelings to her.