James Crocodile Cook

Jim is an expert geologist and archaeologist, having taken part in an excavation of a Tyrannosaurus in the past, and has a crocodile named Karen, initially believed to be a fake by Chronos and Napoleon, who he carries around in a specially-made backpack wherever he goes. Jim regards Karen as "family," and not a pet. He places great trust into Karen and often uses her as a judge of good character, which started his friendship with Juudai. Jim wields a Duel Disk in the shape of a boomerang.

After saving Karen from an animal trap, Jim injures his right eye. After regaining consciousness, he is imbued with the Eye of Orichalcum by a man touched by Jim's devotion to Karen. The man who gave it to Jim told him it was supposed to have incredible powers when in the presence of a special comet. Afterwards, he keeps his right eye bandaged.