One day, my new stepsister arrived after our parents remarried. She was a pure, book-loving girl who was also great at cooking. Though still in her teens, she had a strangely mature charm. One night, I couldn't resist when I saw her sleeping defenselessly under the kotatsu. Despite being family, I gave in to desire, and she willingly accepted me—going all the way to creampie. A heartbreaking story entwining warmth and innocence.