Arthur G6 (アーサーG6 Āsā Jī Shikkusu): A support robot created by Doctor Hoshikawa, Arthur was the one who raised the orphaned children on Earth, becoming the closest thing they had to their parents, giving them everything from food and drink to medical care. He usually aids Fiveman from the Magma Base but at times he can fly out from base and transform into Earth Cannon.