Kid Niki: Radical Ninja is the U.S. name of Kaiketsu Yancha Maru, an arcade game released in 1986 by Irem. In 1987, Data East released ports of the game for the NES, Commodore 64, and Apple II. Curiously, all home versions of the game show screen shots from the graphically superior arcade version on the back of their boxes. It was one of the more successful games released by Data East.

The differences between the Kid Niki: Radical Ninja and Kaiketsu Yancha Maru are minimal. Aside from text translation, the most glaring difference is the main character's hair style. Kid Niki's hair is more "punk rock" with wild spikes and a ponytail in the back. Yancha Maru's hair has more subdued spikes and a topknot (or chonmage). It's also worth noting that in the arcade version of the game, the main character's keikogi is yellow while it is red in the home ports.