Ninja Spirit, known in Japan as Saigo no Nindou (最後の忍道, the final path of a ninja), is a 1988 platform game developed and released in arcades by Irem. Although praised by gamers for detailed graphics, serious themes, solid controls and gameplay, the game also was criticized for its harsh difficulty.

Tsukikage's journey takes him through seven stages, varying from woodlands, wastelands, swamps, temples, and cliffs. Each stage begins with the player slashing their way to the end until they confront a level boss.

The ninja is always armed with the katana named Muramasa (meaning Righteous Cloud), which can be fluidly used to attack in all directions. Extra weapons include the Uzha (meaning Swirling Leaf) (shurikens), the Raitake (meaning Bamboo Thunder) bombs, and the Shoryusai (meaning Rising Dragon) kusarigama. There are also several power-up items, such as one unleashing multiple ninja ghosts to assist the player.