When a Clueless First-Person Shooter Player Falls into Another World Vol 4

MAPPING OUT A NEW MYSTERY With no leads to go on, Schwarz had resigned himself to potentially spending the rest of his life in this fantasy world. But when his skills are requested to tackle a particularly fearsome labyrinth, he learns that a path back home may not be so far away. Though the labyrinths are strange places for the people in this world, a place made up of hospital corridors, trains, and skyscrapers is a pretty familiar sight for a man from Earth. Can he discover why these objects from the real world are showing up while still getting his party safely home?

Source: Penguin Random House API