The eldest sister was utterly defeated. As a former undefeated mixed martial arts champion, gentle yet powerful, I absolutely cannot lose to a bean sprout brat. Hibiki Otsuki DASS-992

Hibiki Otsuki, a former martial arts champion, is now a full-time housewife. She challenges Yuto, a wicked brat who frequents the neighborhood at night, to a fight, declaring, "If I win, you'll have to obey me!" However, Yuto loses the match and, unwilling to accept defeat, secretly slips an aphrodisiac into Hibiki's drink and challenges her again. Under the influence of the aphrodisiac, Hibiki is unable to exert herself and loses to Yuto this time. Although Hibiki challenges Yuto again, he tells her, "If you orgasm, you'll have to obey me." As a result, Hibiki experiences repeated orgasms under the influence of the aphrodisiac, and from then on, becomes his subservient sex slave.