Assassination begins with the events of 1853 when "four black ships" anchored at Edo Bay, sparking civil unrest and the major political manoeuvring that saw the end of the Tokugawa Shogunate. At a time when assassination had become a disturbing political tool, Shinoda's film follows Hachiro Kiyokawa, an ambitious, masterless samurai whose allegiances drift dangerously between the Shogunate and the Emperor.

Based on the famous novel by Yamagami Itaro, this is the story of a group of ronin living in abject poverty in the latter days of the Edo period. Starring the great Konoe Jushiro, Ronin Gai is populated by an ensemble of colorful characters, social outcasts who patronize a restaurant and bar on the outskirts of Edo. Among them are masterless samurai reduced to drunkenness and debauchery. One disgraced and disillusioned former warrior gets a chance at redemption when he is hired to retrieve a famous knife from a corrupt lord. This is the third version directed by Makino Masahiro and is considered a true classic.

On March 11 in the seventh year of Tenpo (1836), a monk named Bennō, who fell in love with a geisha named Oshima, was publicly exposed at Nihonbashi for committing an illicit act with a woman. While this was happening, an extravagant procession led by another monk named Nikkei passed over the bridge. Nikkei, the head of the Kanouin temple, in collusion with Nakano Harima-no-Kami, had schemed to make his younger sister, Miyoshi, the Shogun's mistress and aimed to transform Kanouin into the Shogun's family temple. To fund the renovations, Nikkei accepted bribes from a corrupt merchant named Koya Bunzo.