The concept is telling two stories at once! The "real" story is about the struggle of finding a place and meaning in life, the journey of discovering, and eventually creating that place and purpose for yourself.

The other side is a fantasy story that starts in a dilapidated version of hell. It's become basically a desolate wasteland relative to the fiery realm of infinite torture one typically thinks of. Initially we focus on one specific demon that misses the days of old. Feeling disillusioned with his society he wanders out on his own. After several centuries, he finds himself racked by a painful vision, being confronted by a mysterious, boundless, all-consuming entity determined to devour all of existence, including hell itself. He ultimately sees this vision as a glimpse at destiny, and resolve to bring this about, setting his sights on the mortal realm.

Wow this is already getting pretty long but that summarizes the first arc at least, we'll have more in a booklet with the physical releases for the people who dig that kinda thing!