Ninja Assault is an arcade game developed and released by Namco in 2000. Two years later it was also published as a PlayStation 2 exclusive title with GunCon 2 compatibility. Ninja Assault was developed by Namco, who also created the Time Crisis series. However, this game has more in common with Lethal Enforcers, Virtua Cop, and The House of the Dead series, whereby the movement is completely "on-rails" (i. e. , with no hiding pedal), and the player must shoot away from the screen to reload. Both versions of this game support up to two players in cooperative gameplay.

Once upon a time, in feudal Japan, a seemingly endless war had broken out. And now, the demon shogun Kigai has kidnapped Princess Koto as a sacrifice for his resurrection. But two ninja (named Guren and Gunjo) have arrived as humanity's last hope. Together they travel the demon-infested country to find Kigai, stop him from sacrificing Princess Koto, and save her at all costs. And thus a new war had spawned, humanity versus the demon race.