Japan, 1860. The men of the Mito clan, victims of the Ansei purge, anxiously prowl around the Sakurada Gate of Edo Castle with the intention of assassinating Naosuke Ii of Hikone, tairō of the Tokugawa shogunate and responsible for their misfortune.

After their lord is tricked into committing ritual suicide, forty-seven samurai warriors await the chance to avenge their master and reclaim their honor.