Death March to the Parallel World Rhapsody, Vol. 12 (light novel) — Hiro Ainana

WITH FRIENDS LIKE THESE...With the demon threat neutralized, relative peace has returned to Labyrinth City, allowing the residents to shift their focus back to the labyrinth itself. Between the mysterious chain rampages and the untimely appearances of several areamasters, though, the deeper levels prove more of a challenge than anyone bargained for! Looks like it's time for Satou and the others to head back to Bolenan Forest for some specialized training with the elves!