Onechan wa Game wo Suru to Hito ga Kawaru Onechan  

Onee-chan wa Game wo Suru to Hito ga Kawaru Onee-chan, My "Oneechan"'s personality changes when she plays games, お姉ちゃんはゲームをすると人が変わるお姉ちゃん

Meet Toshi, a typical high school student who was under the care of his beautiful neighbor Yuu-neesan, who lived close by instead of his parents who were often absent. Yuu-neesan was kind and perfect as an adult but had a completely different personality when it came to games. Games weren't just for fun; they could make her angry, naked, and she wouldn't hesitate to use any means necessary. Toshi found himself caught up in the duality of her personality, leading to a surprising new erotic comedy with games and a big sister.