When the Earth and everything on it begins to die, Ruby Heart traces the source to an evil being known as Abyss, the Armor of Erosion. She summons the greatest heroes to her airship to find the being. Ultimately, its source of power is revealed to be a mysterious black metal ball within its center.
The ending suggests that the sphere may be worthless now given the massive crack in it; Ruby holds it in her hand and regards it briefly before throwing it over her back into the water, letting it sink to the bottom. It is not stated if Abyss could return or not.