A homage to Japanese history and mythology, the tale follows the Demon Lord Ōtakemaru, who seeks to kidnap Princess Kōzu, believing she holds the key to granting him ultimate power. To thwart his plans, Emperor Kamu entrusts the warrior Atsushi with the task of escorting and protecting Kōzu beyond the city walls. Along their perilous journey, Atsushi and the princess are relentlessly pursued by yokai and oni unleashed by Ōtakemaru. Meanwhile, Emperor Kamu and the famed general Sakanoue no Tamuramaro struggle to devise a way to finally put an end to the Demon Lord’s reign of terror.
