Moving in next door to the peaceful Komori household is Kikuchi, a man facing his third year of failing college entrance exams. Though honest but socially awkward and struggling to connect with others, Ai and her husband decide to support him as a couple. However, from the very first day they exchange greetings, Kikuchi becomes infatuated with Ai, and one day, after inviting her to dinner, he suddenly pins her down. Witnessing Kikuchi overwhelmed by guilt and regret over his actions—abandoning his studies and deteriorating both physically and mentally—Ai leaves a letter behind, tells her husband his first lie, and decides to spend the night at Kikuchi's place...