Secretly Breeding My Girlfriend's Little Sister Nana Maeno

Nana Maeno, the girlfriend's little sister, is secretly bred by her sister's boyfriend. As the sister is very strict with her boyfriend, Nana Maeno sees an opportunity to comfort him and eventually seduces him into having unprotected sex with her. The boyfriend finds Nana Maeno's approach more comfortable and enjoyable compared to his interactions with his girlfriend. This leads to a series of intimate encounters between Nana Maeno and the boyfriend, with the central kink being the taboo relationship between a man and his girlfriend's younger sister.