Misaki dedicates herself to her husband, Hiroshi, and lives happily, loved and cherished. She believes their relationship is perfect. However, one night, Hiroshi brings home his coworker, Kojima. The two men start playing a card game over drinks, and Kojima proposes a bet: if Hiroshi wins, he gets 100,000 yen; if Kojima wins, he gets to spend time alone with Misaki. Kojima wins. What follows is not mere play—it's a calculated game aimed directly at claiming Misaki’s heart and body.