Yasai Ninja is a 3D hack and slash puzzle/action/platformer. The game is set in Feudal Japan where a Samurai Onion called Kaoru Tamanegui has been incarcerated after finding out his Shogun has committed treason. While in Prison, Kaoru finds an ally in Broccoli Joe. Joe encourages Kaoru to break out and fight. They must travel across Feudal Japan to find allies willing to fight for the cause. The Japanese tribes to forge alliances with include Leeks and the Pepper Rangers, to name a few, and they must amass a big enough army to defeat the treasonous Shogun Kyurinaga and his minions in order to retake Japan and restore freedom back to the people.