I May Be a Guild Receptionist, but I'll Solo Any Boss to Clock Out on Time, Vol. 3 (manga) — Mato Kousaka

The new dungeon, Chalk Tower, is riddled with unpredictable situations! Boss-class foes wandering the halls might not slow down Alina, but the annihilation of Rufus's party at the hands of an unknown enemy stops her and her temporary comrades in their tracks…! Silver Sword reluctantly opts for a withdrawal -- that means escape from adventuring duty for Alina and a return at last to her beloved job as a receptionist! But for some reason, a sense of unease lingers. Meanwhile, Rufus joins Silver Sword as the vanguard, and the party attempts to clear Chalk Tower once more. But do they have any chance against a humanoid monsterwith a Dia Skill?!