Mother-in-law's shameful naked life

Ryoko married Sadao and became the mother of Sadao's stepchild, Mikio. Mikio has been staying at home for a long time, and Ryoko is at a loss as to how to interact with him. Then, one day, Ryoko consults with Sadao about sending Mikio to a rehabilitation facility. However, Mikio overhears their conversation and begins to feel hatred toward Ryoko. Then, when Sadao goes on a business trip, Mikio snatches Ryoko's clothes and forces her to live completely naked. He even uses his friends to play with his mother-in-law, who is embarrassed by her nakedness, even more humiliatingly...