Sega Ninja, originally released as Ninja Princess in Japan, is a run and gun video game released in arcades by Sega in 1985. The game features Princess Kurumi, the titular female ninja, battling enemies using throwing knives and throwing stars. The game was originally released in arcades as Ninja Princess in Japan and Sega Ninja internationally. In contrast to most later games in the genre, Ninja Princess has a feudal Japan setting with a female ninja protagonist who throws shuriken and knives.

Shoot 'em ups are a sub-genre of action games. There is no consensus as to which design elements compose a shoot 'em up; some restrict the definition to games featuring spacecraft and certain types of character movement, while others allow a broader definition including characters on foot and a variety of perspectives.