Khiel's Dungeon

Khiel's Dungeon (キールのダンジョン) is a single-floor underground dungeon created by the arch wizard Khiel a long time ago.

Information
A beginner dungeon that can be reached in a few hours after departing from Axel, the dungeon is a fairly popular training spot for beginner adventurers, being relatively easy and located just a short distance away from Axel. However, since it's pitch-black inside, one will need to use night-vision or some lighting skills to explore the dungeon.

Summary
Kazuma, Aqua, and Megumin take a quest to explore the newly discovered portion of the dungeon as a reward of their vanquishing of Beldia. Kazuma and Aqua end up entering, while Megumin stays behind, and begin their descent into the lower levels of the dungeon. After remarking on the lack of treasure, the duo finally find the hidden passage marked on their map, and descend even lower, to the second floor. There, they find a great deal of undead monsters drawn to Aqua's divine presence, and are forced to battle. Eventually, they come to a room at the end of the hallway they entered, and within meet Khiel, the eponymous creator of the dungeon. He tells them his story, before requesting that Aqua purify him, offering his many treasures in exchange. After he is exorcised, the two of them depart from the room, but are again assaulted by various undead mobs; Kazuma sneaks away using the lurk skill while leaving Aqua to fend for herself.

At a later point in time, the party, this time with Darkness in tow, are sent to investigate reports of miniature clay figures that explode originating from the dungeon.

Trivia

 * There is a secret room within that Vanir uses to store all of the goods he and Wiz (without permission) buy