The Great Cleric 7

Luciel is finally ready to challenge the fortieth floor, but despite his best preparations, things take an unexpected turn after the fight is over. Mysteriously trapped inside the Labyrinth, Luciel endures a grueling six months in the hopes of returning to the surface. Meanwhile, Cattleya and the adventurers fear for the safety of their missing friend—so much so that some familiar faces from Merratoni show up demanding answers.

Volume 7 of The Great Cleric manga series by Hiiro Akikaze.