（Sister-in-law, I wonder if she's okay...） Toshiya, who came to Tokyo to play during summer vacation, decided to stay at his brother's house. He was delighted to see the energetic figure of his brother's wife, Yumi, whom he secretly admired... but that joy was short-lived. He accidentally peeked at Yumi's masturbation. Toshiya couldn't hide his excitement at seeing Yumi's lewd behavior for the first time. After Yumi's marriage, the love he had kept hidden began to resurface and overflow. Following that impulse, he poured out his feelings to Yumi...
