In the north of the metaverse world, there is a mythical monster arena "Deep-Oasis".
A thousand years ago, "titan-X", a wandering colonist from an alien civilization, start large-scale mysterious biological experiments and suddenly disappears quietly without carrying anything.
Adventurers from all over the world, seeking the magical ore which titan-X left behind - The Rune. By pouring power into Rune, adventurers can summon powerful monster "Saga" with supernatural powers and only fight for its master.
People who want power and fortune are flocks to "Deep-Oasis", summon their own Saga team and fight for it.