The Yellow Devil was a creation of Dr. Wily 's that guarded Wily's Castle . It attacked Mega Man when he tried to get to Dr. Wily. Mega Man was going to defeat it by giving it a thunder beam to the eye, but changed back to using his mega buster as it was the one weapen Dr. Light trusted him with from the beginning. Mega Man thought he had defeated it after shooting its eye, but it reformed and was defeated by a second shot to the eye.