【Published as a book by TO Books. Volume 2 of the novel (print and digital) is now on sale. Volume 3 of the manga is also on sale. A manga adaptation has begun serialization on Corona EX, TO Books' official manga publication site.】

I woke up in a forest. It seems I've become a ghost. I appear to have memories (or rather, knowledge) from before I died. From there, Shu Arklight's story began.

He steals magic power with the power of Life Absorption, accumulates it, and evolves. He analyzes magic to boost his combat strength.

This is the story of a protagonist who came to be called the Underworld King, and his partner witch, as they travel the world and do various things.