Creampie incest mother and child humiliating copulation

At the bar where she works, Maki begins to have a physical relationship with Kengo, a regular customer. One day, with her son's arrangement, she invites Kengo as well and the three of them decide to go to a hot spring together. However, her son is present at the repeated love affair with Kengo at the inn, and he leaves without saying a word. Maki is flustered, not knowing that it was all according to her son and Kengo's plan... Later, Maki falls asleep after getting drunk by Kengo at a bar. When she wakes up, she is tied up in a cage, and outside the iron bars is her son with a distorted expression...