(I wonder how my sister-in-law is doing...) Toshiya, who came to Tokyo for summer vacation, ended up staying at his brother's house. He was happy to see his brother's wife Yumi, who he secretly admired, looking healthy, but his joy was short-lived... he accidentally saw Yumi masturbating. Toshiya could not hide his excitement at seeing Yumi's lewd behavior for the first time. After Yumi got married, his suppressed feelings of love for her came back to life and began to overflow. He gave in to that impulse and confessed his feelings to Yumi, but...