The wildly popular novel by popular author Nyaano's Esa x Fitch, which has sold over 270,000 copies, is now a live-action film starring Kashiwagi Konatsu! Tatsuya visits his girlfriend's family home to tell her about his marriage. There, he is reunited with her younger sister, Benihana, whom he used to look after when they were little. Unlike her innocent youth, Benihana has grown into a fully grown woman after seeing her for the first time in a long time. That night, Tatsuya and his girlfriend, Yuba, are enjoying a drink together, but she falls asleep early. Watching them, Benihana seduces Tatsuya next to her sister. Tatsuya's reason wavers, and despite feeling guilty, they end up having a physical relationship...