Shota moves into a new family after his mother remarries, gaining a new father and an older sister. As he adjusts to his new environment, he finds himself frequently touching his kind and cute sister's beautiful buttocks. Whether during nighttime mixed bathing or playing cards, Shota plays mischievous pranks or acts innocently, but his sister always responds with a gentle smile. Then, when Shota innocently asks, "What is sex?", an incredibly realistic and natural conversation unfolds. The dialogue grows erotic, exciting the reader and stimulating their imagination. A must-watch for fans of Shota.