In this collaboration between SODstar and Peach Family, Hikari, a college student's sister, has secretly been attracted to her younger brother. Determined to act on her feelings, she boldly enters his bath while he's soaking, marking their first time together in ten years. Initially surprised, the brother becomes aroused as they share the intimate moment. They eventually cross the line and begin exploring each other's bodies, leading up to an unprotected creampie climax... *Note that recording contents may vary depending on distribution method.