Dux states that he was introduced to and trained in Koga Yamabushi Ninjutsu by Senzo Tanaka. Dux's martial art style, Dux Ryu Ninjitsu, is not a koryu (15th century feudal form of Ninjutsu), but is still claimed to be "based on its Koga Ninja root principles of adaptability and consistent change". Frank Dux taught a technique he calls DUX FASST (Focus-Action-Skill-Strategy-Tactics).