Rukifellth was not actually the evil one; he became possessed by the demon, Sthertoth, when he touched the Celestial Stone (which Sthertoth was imprisoned inside) on Planet Kaos. He turned the seven Elemental Knights evil and sucked planets into a Black Hole while searching for the Elemental Stones so he could return to power. Bomberman fought Rukifellth and defeated him, however, Rukifellth knew that whether the Astral Knights beat Bomberman or lost to him didn't matter; either way, the Stones would still be in the same place as him, allowing him to use the Celestial Stone and become Sthertoth again. Rukifellth vanished at this time, but was returned to normal along with Lilith after Mihaele merged with Sthertoth into the Angel of Light and Shadow, who, after being defeated by Bomberman, vanished to lay dormant realizing Bomberman would protect the universe.
In an alternate ending, Sthertoth imprisons Mihaele and transforms, but is defeated and is seemingly killed, returning Rukifellth to normal; however Sthertoth reawakens, killing Rukifellth, and destroys Warship Noah, killing Lilith while only Bomberman and Pommy escape.