It all began a century ago, when the ninja clan made a truce with the Underworld. But now, after a long peace, the people of the Underworld are about to have a new ruler. The ninja Miko Mido is suddenly entrusted with the family business of making sure that the sex-crazed Shikima does not copulate with humans. But when a rival clan stole the seal that symbolized this demonic deal, Miko and her sister Miyu became the sexual target of the most dangerous race of perverts that ever existed on earth. What can a girl do? Fight, using all her martial arts and sexual magic.