In the city of Edoropolis, hundreds of mechanical animals live in harmony alongside each other. However, when Lord Wanko discovers that the shogun's chief advisor, Lord Korn, is plotting to take over the government, he knows that something must be done to preserve the peace. In order to thwart Korn's plans, Wanko forms the Nyankees—an elite ninja team led by the fearless Yattarou, who wields the mystic sword Masamasa. With all this power, the Nyankees seem unstoppable!

But Korn's schemes are not the only thing the team has to worry about. Secretly based out of the popular Pizza Cats restaurant, the Nyankees must keep their operations hidden while delivering piping-hot plates of pizza and justice.