Sumilidon is Koji's Medabot. He is not much of a talker, usually only speaking when spoken to or when it is extremely important. He is a strong contender and his specialty is the Shadow Sword. During the robattle with team U.S.A. Sumilidon gained the ability to use the Medaforce, though many believed that it was because he had a rare medal that was not the case as Dr. Aki ran multiple test on Sumilidon's medal and the results being inconclusive. It is never truly explained how Sumilidon could use the Medaforce Dr. Aki had a theory that Sumilidon might have had some ancestral connections to the rare medals giving him the Medaforce but this is just a theory.