My Sister's Seduction (妹たちの誘惑 Imōto-tachi no Yūwaku) is the 3rd episode of the Kono Naka ni Hitori, Imouto ga Iru! anime series.
Konoe and Miyabi visit Shougo Mikadono to teach him to love women, after they mistakenly saw Ikusu on top of Shogo the day before. The two girls treat Shogo as their older brother, clinging to him throughout the day. At night, they undress from their pajamas on his bed, making him so uncomfortable that he is unable to sleep. The next day at school, he tries to avoid them and hides in the student council office. Mana Tendou, the student council president, suggests Shogo to become friends with Konoe and Miyabi, since he cannot date either one. Later on, after accompanying Miyabi to shop for a bathing suit for her, they run back to her place soaking wet from the rain. While he prepares to take a bath, he suspects that Miyabi may be his little sister, after taking notice of the toy shampoo bottle. She admits wanting to marry him, but he turns her down due to the suspicion.