Sleeping with my friend's mom, feeling ashamed not wearing a bra, Miki Matsuzaka JUX-523

Kenji, the son who transferred schools, brings his friends over. His mother, Miki, greets them with a smile, but one day she notices a bra hanging out to dry is missing and begins to suspect her friend, Satoru. The school's headmaster, who knows about this, decides to plot revenge against the Matsuzaka family...