Sho Kosugi is a Japanese martial artist, actor, filmmaker and writer with extensive training in Shindō jinen-ryū Karate, Kendo, Judo, Iaido, Kobudo, Aikido and Ninjutsu. A former All Japan Karate Champion, he gained popularity as an actor during the 1980s, often playing ninjas. He starred in a trilogy of martial arts ninja films produced by Cannon Films, before starring in the primetime television series The Master. His work helped establish ninjas in popular culture, leading to a "ninja boom" or "ninjamania" during the early-to-mid-1980s.