The first animated adaptation of Pin-Point's fetish CG series follows adult academy role-play characters Shizune Yukihira and Takuma Ota. Shizune is a beautiful, brilliant young lady admired across the academy, but she secretly loves anal masturbation and becomes intensely aroused by degrading herself for it. Reclusive anal obsessive Takuma secretly records women in the academy restroom and ranks their anuses. When Shizune discovers his secret, she shocks him by asking to have her own anus trained. Her tight opening is gradually stretched and conditioned as the seemingly refined beauty is transformed into an anal-obsessed submissive.