Kid Niki: Radical Ninja, known in Japan as Kaiketsu Yanchamaru (The Wonderful Yanchamaru), is an arcade game developed and published by Irem in 1986, and was later published outside Japan by Data East in 1987.

One day in Feudal Japan, Kid Niki, the most radical of ninjas, is training at his Ninja School. Suddenly, a passing bird is struck down by an arrow and lands at Niki’s feet. Attached is a note explaining that Niki’s girlfriend, Princess Margo, has been kidnapped by the evil Stone Wizard. With the cry of “Will help you!” Niki bursts through the wall of his school and sets off on his quest to save Margo.