Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka OVA

After surviving the crisis on the dungeon's 18th floor, Bell Cranel and his companions begin the long climb back to Orario. Their exhausted group takes an unexpected detour when they discover an unexplored chamber containing something no adventurer expects to find underground: a warm, inviting hot spring.

The chance to rest is too tempting to refuse, and the expedition briefly turns into a bathhouse holiday. Yet the strange spring is not as harmless as it looks. As odd behavior and an increasingly suspicious atmosphere spread through the group, Bell must discover what is really hidden in the water before their relaxing break becomes another dungeon emergency.