Recently, Mio feels that both her husband and wife are weakening their physical strength. The night's life had also become bland. Mio started doing light exercises and stretching to build up her strength. As I was stretching, I saw my son in the hallway. Mio called her son and stretched with her. The son gets an erection when he sees his mother's ass bouncing with a balance ball. Mio noticed that her son had an erection. That night, Mio, who can't get her son's erection out of her head, masturbates in the kitchen. My son who saw it ...