Ninja Gaiden Shadow, known as Ninja Ryūkenden GB Matenrō Kessen (忍者龍剣伝GB 摩天楼決戦? lit. "Legend of the Ninja Dragon Sword GB: Skyscraper Decisive Battle") in Japan and Shadow Warriors in the PAL region, is an action game released for the Nintendo Game Boy in 1991 by Tecmo. It stars Ryu Hayabusa and is part of the Ninja Gaiden series. The game is often believed to be a licensed edit of Shadow of the Ninja, a proposed Natsume ninja game that Tecmo altered the game to fit in with the Ninja Gaiden console trilogy.