Sumo was uniquely honoured among the relatively few pupils selected to train under the ancient Samurai known as the Enlightened One. His master permitted him to sip the Enlightened One's potion of power, and, before a year had passed, Sumo was transformed into a giant fighter and master swordsman. Sumo the Samurai pledged loyalty to Japan's Emperor Hirohito and battled the American All-Star Squadron during World War II as Hirohito's personal agent. Along with the shape changing Kung and Tsunami, Sumo was a member of the Samurai Squad. Sumo remains a legendary figure in the land of the Rising Sun, but his present whereabouts are unknown. He made a cameo appearance during The Crisis On Infinite Earths, but most of his recorded whereabouts have been during World War II.