Steamy incest - Mother and child bathing

My mother, Sae, recently in puberty, felt that her son's gaze at her was different than before. Of course, I have told him it was just my imagination many times, but I am not satisfied... One day, when Sae gets out of the bath, he comes in with his son in the changing room. "What's wrong?" he called out, but realized that his son was acting strange, and when he suddenly looked at his hand he was clutching Sae's underwear he had taken off tightly...