Yukina, an OL troubled by constipation, casually participates in a constipation treatment camp she learned about online. However, it turns out to be an enema-soaked anal abuse exercise class run by an SM perverse trainer. To improve constipation, the muscles around the anus, the anal sphincter, must be strengthened, and the shy woman's anal opening is forcibly trained! Expansion, foreign object enema, anal sex, and the merciless punishment by the female trainer. The woman is relentlessly humiliated and tormented at the anus, repeatedly experiencing masochistic enema play.