Shy and troubled by the changes of adolescence, Minoru struggles to express his feelings. Unaware of her son's inner turmoil, mother Izumi worries only about his studies. As Minoru's confusion grows, impure fantasies about his mother's voluptuous, soft body begin to stir, leading him into a daily obsession with masturbation while clutching her lingerie. Soon, she notices her underwear mysteriously disappearing, sighing in quiet frustration. One day, she catches Minoru red-handed as he rummages through her lingerie drawer. In that instant, their relationship takes a shocking, irreversible turn—