My Beloved Sister Was Cuckolded

A story-driven adult game set in a rural village. You play as Yūki, who develops a romantic relationship with his non-blood-related older sister, Kotohá, a college student working at a used bookstore. As their relationship deepens, Yūki begins receiving mysterious adult videos resembling his sister on his phone, while local men show increasing interest in her. The game explores themes of jealousy, infidelity (NTR), and relationship drama through animated adult scenes and branching narrative choices.