A terminally ill girl named Himari Takakura is miraculously saved from death by a strange spirit who resides in a penguin-shaped hat. However, in exchange for extending her life, the spirit tasks Himari's brothers, Kanba and Shōma, to seek out an elusive item known as the Penguin Drum with assistance from a trio of strange penguins.

With a demonic, soul-consuming weapon in hand, can a legendary swordsman and a samurai brotherhood defeat a bloodthirsty zombie uprising?