A daily shopping outing between an older sister and her younger brother kicks off a project to deepen their bond. The brother is Harunobu, a 21-year-old university student. The older sister works in the apparel industry and has a naturally warm, outgoing personality due to her job. They begin by chatting about favorite foods, gradually escalating to intimate questions like "Do you have a boyfriend?" and "Have you ever kissed someone?" Harunobu views his sister as a romantic interest, following a classic "siscon" storyline. The sister is kind and nurturing, gently guiding her awkward younger brother through their conversations. As flirtatious questions arise, they move into grinding, eventually leading to creampie sex. This erotic narrative portrays the deepening relationship between siblings, exploring the tension between familial bonds and romantic desire, step by step.