Dr. Go (Full Name: Mantaro Go) is the main antagonist and a major antihero. He is an eccentric inventor who wishes world domination by creating cyborg cats as weapons of mass destruction. His plan completely backfired when Kuro was created with a full will of his own. He later stops from his plans in world domination and decides to live in a more peaceful way of living with Mi and later Kotaro. He maintains a friendly rivalry with Kuro. He was voiced by Tōru Furusawa.