I May Be a Guild Receptionist, but I’ll Solo Any Boss to Clock Out on Time, Vol. 1 (light novel) - Mato Kousaka - Bog

Alina Clover signed up to be a receptionist for the Adventurers Guild thinking it would be her ticket to the good life. Unfortunately, her dream gig turns into an overtime nightmare whenever the adventurers get stuck clearing a dungeon. To save herself from a mountain of paperwork, Alina takes to beating down monsters herself to solve the problem! Now she just needs to keep her activities a secret...