Nathaniel Cooke holds a 2nd-degree black belt in Bujinkan Taijutsu and is an instructor at the Budo Warrior Schools.
Robert Twigger is a British author and explorer who has been described as "a 19th-century adventurer trapped in the body of a 21st Century writer." He attended Oxford University and later spent a year training in Martial Arts with the Tokyo Riot Police. He has won the Newdigate prize for poetry, the Somerset Maugham award for literature and the William Hill Sports Book of the Year award. He currently lives in Cairo, Egypt.