"Using my hand doesn't count as having an affair, right?" (This is followed by unrelated text fragments: "My girlfriend's younger sister, a little devil, masturbated and rubbed me at my Sanlianbo apartment, leading to my 19th ejaculation and being taken away by her," and "Ono Rikka MIDA-106.")

The girls I've liked in the past (I don't have much dating experience) all had one thing in common: I liked their inner qualities more than their looks. But now, my girlfriend's sister is the cutest woman I've ever met, and it's bothering me. Because her sister is secretly seducing me... Even though it's something to avoid, she's just too cute... I might get distracted by my girlfriend and fall into a trap... Her sister, Rikka, insists that masturbation isn't cheating and keeps getting close to me. Although I feel guilty towards my girlfriend, I feel both ashamed and excited after being seduced by Rikka's masturbation...