Shiishii Hinnyuu Shimai

Tomokage used to live with his grandfather and grandmother due to some reasons. But he comes back to his hometown for the first time in ten years after they pass away. When he enters his house, Chinatsu, his younger sister, and Mizuho, his older sister, welcome him. They have a welcome-back party, but there aren't his parents. According to them, his parents are now abroad on business. With Chinatsu, who always nestles up to him, and Mizuho, who suddenly tries to help him masturbate, his new life begins....