The Labyrinth city of Orario has a massive dungeon at its heart, filled with terrifying beasts. A new adventurer, Bell Crannel, challenges this perilous labyrinth, but not in hopes of finding treasure, but in hopes of picking up a girl.

A massive floor boss has crashed down from the upper floors and begun tearing apart the adventurers. Aiz has left for the surface, and it's up to Bell and his friends to defeat the monster. With their escape route cut off, it's do or die if they ever want to see the light of the sun again.