In the past evil superhumans invaded earth to conquer the human race. A group of superhuman calling themselves the muscle league challenge the evil. One of the muscle league member, King Muscle displayed great strength and skill. With his help the muscle league defeated the evil and once again peace retuned to earth. 28 years later a new evil force has come to conquer the human race, but legendary heros who fought in the past were too weak and old to beat the new threat. Now they trained a new league of warriors to fight.

One of the warriors is Kid Muscle the son of the legendary King Muscle. He and the new generation are the only hope for the human race against the new threat.