Isekai Walking: Volume 4

At the behest of the mysterious librarian Seris, Sora and his party are going all in on conquering Majorica’s dungeon. With the help of the newly arrived Chris and Rurika—as well as another group of old friends who happen into town—they make steady progress through an increasingly difficult series of labyrinthine floors punctuated by verdant grasslands, rocky ravines, and a forest lake swarming with undead hordes. But as the party comes closer to their goal, a new intrigue begins to take shape behind the scenes. Dark forces are plotting things in the dungeon’s depths, and their target is...Layla?! Sora will have to race against time, not just to prevent a monster parade but to save his old friend too!

[From J-Novel Club]