Much like other games from the same timeframe, such as Gunstar Heroes, the game's story varied between the Japanese language release and its English language counterpart. In all versions of the game, the events take place in the Valdi System, where an evil space pirate, Kaiser Greedy, has used mind control to make the planets' leaders obey him.

In the Japanese version, the inhabitants of Planet Neer (Flora in the English-language version) pray for a hero before Greedy's mind control minion, Rhio, snatches the planet elder. The desperate prayers reach the nebula of the Star Goddess, Oruto. She awakens one of her children, Ristar, with the sole purpose of granting the wishes of the innocent people. He must stop Greedy and the brainwashed leaders of each world in the galaxy to restore peace to the galaxy.

In the English-language version, Oruto is omitted altogether. Instead, Ristar has a father figure, the Legendary Hero, who is a shooting star that protects the Valdi System. Rather than Oruto awakening Ristar, the Legendary Hero was kidnapped by Greedy, and it is up to Ristar to rescue his father as well.