Staying at his older brother's house while preparing for college entrance exams, Taichi finds himself completely distracted by his sister-in-law Sumi Kurokawa's slender body and voluptuous ass. One day, he accidentally catches her masturbating through a crack in the door. Unable to forget the sight of her writhing bare ass, Taichi sneaks up on Sumi the next day as she works in the kitchen and forcefully takes her from behind. Though she resists at first, overwhelmed by his rough, pounding thrusts, she gradually succumbs to his intensity.