The Black Moon is where Ra Devil resides, biding his time until he has all four Elemental Crystals in order to transform into Deathgyunos. The heroes travel to the Black Moon with the help of Hyriuu to stop Ra Devil.
For most of the story, the Black Moon sits ominously in the sky above Planet R. It's where the hollow body that is destined to become Deathgyunos lies dormant, until Ra Devil can become one with it. In order for the heroes to travel to the Black Moon, they must find the dragon Hyriuu below Tycoon. Once Hyriuu has grown to his full size, the heroes travel through space to reach the Moon and face off with Ra Devil.
However, Ra Devil has already succeeded in attaining the four Crystals and draws upon powerful Cosmic energies to bring Deathgyunos to life. The energy converges on the Black Moon and the God of oblivion is reborn.
When the heroes reach the Black Moon, they find it barren and destroyed. They face off with Deathgyunos among the ruins of the Moon, and after many battles succeed. In the end, Prettz, Linaly, Rouge and Valkus all head back to Planet R once the threat of the Black Moon is neutralized.
- The ruins and broken highways that litter the Black Moon would suggest that there was once a civilization there before Ra Devil.
- Only Ra Devil's ship and Hyriuu are able to travel between the Black Moon and Planet R.
Black moon is a reference to witchcraft which bears no significance to astronomy.