Strange Adventure of a Broke Mercenary (Light Novel) Vol. 8

Loren's enigmatic partner Lapis never did explain how the enchanted great sword in her family's keeping mysteriously found its way into his hands. But no matter how Loren likes to let Lapis keep her secrets, some tales must be told. Together, they set off to the fabled lands ruled by demons. But first they'll have to make it through the cave system that protects demon kind from the rest of the world, which quickly proves as immense as it is deadly?