Kid Muscle (or Mantaro for short) also known as Kinnikuman Nisei, is a bumbling, gross, and wimpy sort-of person. Unfortunately, he has been summoned to protect the earth from the evil dMp, a band of cheating wrestlers from outer space. Luckily he's not undertaking this task alone. Kid Muscle must join the Muscle League, a group of wrestlers from outer space who are training themselves so they can defend the earth, and stop the dMp by achieving "Ultimate Muscle", a hidden power that makes Mantaro an almost unbeatable opponent.

Kinnikuman, ou 'Muscle Man', est un super-héros pour le moins original : maladroit et plutôt faiblard, il est le premier pour se retrouver dans des situations incongrues… À force de rencontres et de combats, notamment sur le ring, Kinnikuman va tenter de devenir plus puissant.

Pas de synopsis pour le moment.