Hoshikawa Rindoru is kidnapped by an acquaintance due to her irresistible cuteness. Though initially terrified, she begins to feel masochistic excitement as a femboy being treated like an object. Gradually, she is transformed into a living cumdump solely for sexual gratification. Her anus is trained to the point where it can no longer survive without male semen. Driven by pleasure, she willingly embraces the path of a sex slave.