Intrigued by his girlfriend Sakurako's secret life—a yoga instructor older sister who is a true siscon—the protagonist arrives to meet her family. The atmosphere immediately turns tense; Sakurako’s parents react with rigid disapproval toward their budding romance. Later that night in a dreamlike state of sleepwalking arousal (or perhaps just deep slumber), he witnesses Yuko shine an enigmatic light onto Sakurako. The next morning brings cold dismissal; Sakurako acts like he's a stranger and kicks him out of their home.
Suspecting the truth behind this sudden rejection—that Yuko is manipulating things—he steals her mysterious flashlight. Unable to master its power to restore their intimacy with Sakurako alone, he waits until fate intervenes: Yuko tracks him down to his residence and begins ransacking his place searching for the device. During their heated confrontation over the stolen prop, something unexpected happens: he accidentally hypnotizes her! A triumphant plan of revenge against the manipulative sister is born.
Feeling utterly victorious as his hypnotic control solidifies, the protagonist basks in his success, unaware that the game has only just begun. This scene delivers intense familial tension blended seamlessly with powerful mind control and escalating sexual dominance. If you love stories where one partner gains ultimate leverage over their girlfriend's seductive sibling, look no further!