Onee-chan wa Game wo Suruto Hito ga Kawaru Onee-chan

Toshi is an ordinary high school student. With his parents rarely around, he spends his days being cooked for and tutored by his beautiful neighbor, Yuu-nee. She’s kind, caring, and the very picture of a perfect working adult. whenever games are involved, she becomes a completely different person...!? She's not playing around! She will rage, strip, and do whatever it takes to win!