Masakazu had returned home after a failed business venture, the only one who treated him kindly was his sister-in-law, Kaho. During the hot summer, Masakazu grew frustrated with his job, so he often came home early. He would steal glances at his sister-in-law doing housework, and when she was sleeping in her sexy pajamas, sweat dripping down her body from the heat made him incredibly desire her, and he constantly thought about making love to his sister-in-law. Then his limits reached their breaking point; he could no longer restrain himself when he was alone at home with his sister-in-law.