An assassin for a secret organization keeping Japan safe from underworld threats finds himself targeted by evil forces aiming to unleash an unstoppable criminal syndicate upon Japan.

A girl finds an old handgun in her attic and the symbolic object conjures a mystical scene of samurai (a stellar cast of actors joined by the 20-person Edo punk band Seppuku Pistols, who also provide the soundtrack) gathering within the moss-grown location of Kasosan Shrine in Tochigi Prefecture.