Kid Muscle, also known as Mantaro, is a bumbling, gross, and somewhat timid individual who is summoned to defend Earth from the evil dMp, a band of unscrupulous wrestlers from outer space. Fortunately, he does not face this challenge alone. Kid Muscle joins the Muscle League, a group of extraterrestrial wrestlers training to protect the planet, and must unlock the hidden power known as “Ultimate Muscle” to become an almost unbeatable opponent and defeat the dMp.