Living in an average Japanese household, 19-year-old Kazuya Imawizama seems to be a normal teenager; but in reality, he has an incestuous and unquenchable lust for his 16-year-old sister, Fumiko. His obsession for her goes so far that he even masturbates to his sister bathing from the hidden camera he installed in the bathroom. However, it turns out that Fumiko has always known of her brother's indecent and immoral activities! Naturally, Kazuya is shocked at this revelation, but he soon becomes strangely aroused when Fumiko insists that he watches an amateur porn video featuring none other than herself... [Written by MAL Rewrite]