Deep in the mountains of feudal Japan, a group of children endure cruel and unorthodox training in order to become the Shogunate's most secret and deadly weapons - the Demon Spies! Their true identities are hidden - even from each other. Behind their demon masks, they are educated in the deadly arts of infiltration, espionage, assassination - and seduction! If they survive to become strong enough to kill their teachers, they will become - the Demon Spies! Sent on a suicide mission to uncover a deadly conspiracy, five inexperienced Demon Spies must infiltrate a powerful fief, discover the location of its secret arsenal, and destroy it. But Lord Shogen, the Demon Hunter, plans to brutally interrogate, ingeniously torture, and cruelly execute - the Demon Spies!