Mai is a kunoichi who inherited the Hiwashi-ryu ninjutsu tradition. Once involved in a succession dispute, she withdrew and instead taught martial arts to villagers in the ninja village. One day, her master Jinzai goes missing. Seeking clues from her senior brothers Gourei and Hourai—both defeated in the succession struggle and now rogue ninjas—Mai descends to the village's lower town. However, she discovers Hourai and his allies have taken control of the village, using the villagers as test subjects for human experiments. To strip Mai of her rightful inheritance, Hourai and his group ambush her using Hiwashi-ryu erotic techniques, ensnaring her in a trap of utter humiliation. Ultimately, Mai meets a tragic BAD END.