Under the rule of Shogun Ienari, the samurais and the townspeople are all discontented and grumbling about their lot in life. Amidst all these, there lives a man by the name of Jirokichi, popularly known as Nezumi Kozo. Jirokichi runs a bar with the help of his sister, Kosode. Unbeknownst to everyone, Jirokichi and Kosode are always helping the victimised weak and poor from being bullied by the evil rich.