The peace never lasts. Wataru thought he was done being a hero, thought he could just be a kid again, but the world won't let him rest, and the show knows that's the real cost of being chosen. Doakudar's brother isn't just a stronger version of the last threat; he's proof that victory doesn't close doors, it opens them onto harder questions. A boy who wants to go home discovers that home stopped being a place the moment he learned what he could do.

After defeating Doakudar, Wataru has been living happily on Earth. One day, while he is playing with a friend, Ryujinmaru appears and asks him to fight again. The seven star mountains that feed the rainbow of Mt. Soukai have been seized by Doakudar's brother, and this new foe is even stronger. If every one of those mountains goes dark, the rainbow will vanish and everyone will be left in darkness forever. Wataru must travel through all seven and bring down his new enemy. This sequel to Mashin Eiyuuden Wataru mixes adventure and comedy with giant robot action across 46 episodes.