An innocent young man named Ikuroo has a parasite called Baoh implanted in his brain by the evil organization Doress. This parasite renders him nearly immortal and grants him the ability to transform into a highly powerful beast when he is in trouble. Doress intends to use him in some sort of scheme for financial gain, world domination, or something similar, but while they are transporting him on a train, a young psychic girl named Sumire (who is being held by the organization because of her abilities) sets him free, and the two escape together. Naturally, Dr. Kasuminome is the mad scientist behind the entire Baoh project, and he is not about to let his test subject get away; he has considerable resources at his disposal, including some superpowered lackeys as well as a small army.