Your Sister

Yuuka has just begun dating Kouta, the childhood friend she has always been infatuated with. As they reach the two-month mark in their relationship, they decide to visit Kouta's house to engage in intimacy for the first time. However, their lack of experience leads to complications. Just as Yuuka feels troubled, Kouta's younger sister appears before her and says, "Become my ideal girl." With a boyfriend, a girlfriend, and his younger sister involved, a love triangle emerges that is both captivating and morally questionable.