Made in Abyss Official Anthology

The enormous cave system, known as the Abyss, is the last unexplored place in the world. Nobody knows how deep down goes this titanic pit, inhabited by strange and wondrous creatures and full of mysterious ancient relics which purpose in unknown to modern man. Generations of bold adventurers have been drawn by the cryptic depths of the Abyss. In course of time those brave enough to explore the dangerous pit came to be known as "Delvers."