Iori, an OL living with her fiancé, was growing increasingly dissatisfied with his refusal to have sex without protection until they got married. One day, she happened to meet Murai, who lives upstairs, and blurted out, "I want to have sex without protection." Unable to refuse Murai's invitation, she finally experienced the sensation of a real penis for the first time in her life, becoming addicted to the pleasure of internal ejaculation…
