As the Demon Slayer Corps members and Hashira engaged in a group strength training program, the Hashira Training, in preparation for the forthcoming battle against the demons, Muzan Kibutsuji appears…

As a lionhearted boy who can’t wield magic strives for the title of Wizard King, four banished Wizard Kings of yore return to crush the Clover Kingdom.

When the evil Dr. Hell attacks the Earth, the mighty giant mecha Mazinger Z is formed to stop him.