Kozo's daily life in a boring country town is transformed by a terrifying attack by a marauding army of Monster Girl warriors. While trying to escape the sexy and scary Mea, as Kozo is trying to avoid Mea's magical explosions the cave system collapses sending him deep into its uncharted depths. As luck would have it this newly revealed area of the cave contains the magical treasure of a legendary thief, The Silver Rat, through which our hero is bestowed with the skills of the master thief! After turning the tables on Mea and successfully seducing her with his own brand of sexy skills he sets out on his own quest to steal the loyalty, and virginity, of the entire Monster Girl army and to claim his very own Monster Girl harem! Dark elves, Onis, Wolf girls, a dragon and more! With the powers of The Silver Rat on your side all the sexiest monster girls are yours for the fucking!