Robotics expert Dr. Otoi built Signal, a robot, to be a companion for his grandson, Nobuhiko. However, a mishap during construction causes Signal to occasionally become a baby whenever the grandson sneezes! Soon Pulse appears, one of the Doctor's previous creations, Pulse was the prototype for Signal so he is weaker in strength and abilities. Despite being critically nearsighted, Pulse is loaded down with weapons and has been reprogrammed by Dr. Otoi's mysterious rival to kill Signal.