Nanase moved from her hometown of Okayama to Tokyo for college and ended up with housing troubles, so she had to stay at her sister's apartment where her sister lives with her boyfriend. After leaving her parents' home, Nanase became interested in various things, and surprisingly, she developed an interest in her sister's boyfriend, Yuta... Cute, big-breasted, no bra! This story of a sister who becomes increasingly erotic is like a dream come true!
