The Shadow Master (in Japanese: シャドー・マスター) is the main antagonist of Shinobi III for Sega MegaDrive, and the final boss of the game. As the true Overlord of Neo Zeed, he is a villainous super ninja with skills very much like Joe Musashi's own. With powerful ninja skills combined with a body enhanced by Zeed's secret Science Department, it is rumored that he is cloned from Musashi's own bloodline. Having become fed up with Musashi's constant interference he seeks to destroy him, knowing that he is the only ninja alive capable of thwarting his plan of conquest.
The Shadow Master appears as a ninja dressed in a dark red shozoku wearing cybernetic armor. In closer expection, it appears similar to the armor of the Shredder from the famous Teenage Mutant Ninja Turtles series. After recieving enough damage, his suit turns bright red, indicating that he's fighting at full power, enabling him to use cybernetic weapons.
The ultimate advancement of Neo Zeed combining Zeed's Biotech research with advanced Shinobi Arts, the Shadow Master is an evil super ninja that is the true master and overlord of Neo Zeed. After Joe Musashi defeated Neo Zeed 2 years ago and became the new chief of the rebuilt Oboro Ninja, it was then discovered that the Ninja Master was just a figurehead for NEO ZEED. It's true mastermind was the mysterious dark ninja known only as the Shadow Master, a deadly shinobi cyborg technologically enhanced, and rumored to be cloned from the Musashi bloodline.
After calling his cohorts into a meeting he issued an order. "For us to attain our dream of world domination, kill our hated enemy Joe Musashi!".
After his attempts are foiled, he faces Joe Musashi in the ZEED Aeroship, the Wing of Darkness. After changing the room's virtual reality chamber to his liking, the evil shinobi proceeded to attack. Initially on equal ground with Musashi during the battle, he gained a power up from the energy of the room, and became deadlier as the battle raged. Eventually he would meet his ultimate fate at Musashi's hands, with his core overloaded the Shadow Master self destructs, causing the Wing of Darkness to malfunction and self-destruct as well. the Overlord of Neo Zeed perishes in the blaze as the sky fortress crashes and burns away.
The Shadow Master is a secretive and even very silent individual whose identity he entrusts only to his closest NEO ZEED members, Karura and White Lion. He desires to rule the world with fear and intimidation, and to usher in a new age where the Ninja rule the world from the shadows. Those who serve him well are rewarded with praise, wealth, power and status, but those who fail him, he punishes ruthlessly with hideous forms of torture such as making them guinea pigs for NEO ZEED's cruel and inhuman biotechnology experiments, or kills them slowly and painfully.
His grievances with the Oboro are many, especially Joe Musashi, who has ruined his plans time and again. To finally achieve his ambition of world conquest, he will stop at nothing to destroy Joe Musashi and end the legacy of the Oboro clan.
- The Shadow Master is the only boss with a win pose. If the player dies when fighting him, the Shadow Master simply stands with his arms folded in satisfaction.
- The Shadow Master's identity is left untouched upon by many, but the fact that he knows Musashi's Oboro Style is the same as Nakahara, showing that he is in fact the original Masked Ninja, revived in cyborg form after his first death.
- Shadow Master's title is shared with Jiro Musashi's master; but his counterpart's appearance is based on the Ninja Master and Byakushishi.