During the Edo period, Japan is suddenly invaded by alien creatures known as the Amanto. Despite the samurai's attempts to combat the extraterrestrial menace, the Shogun soon realizes that their efforts are futile and decides to surrender. This marks the beginning of an uneasy agreement between the Shogunate and Amanto, one that results in a countrywide sword ban and the disappearance of the samurai spirit. However, there exists one eccentric individual who wields a wooden sword and refuses to