Is It Wrong to Try to Pick Up Girls in a Dungeon? On the Side: Sword Oratoria, Vol. 19 (manga) — Fujino Omori

Monsters. Fundamentally different from humans and beasts, these loathsome creatures make their homes underground. To Aiz, such beings only exist to be destroyed, so when they suddenly appear in Orario, she doesn't hesitate to leap into action.
As chaos erupts in the streets, Loki Familia rises to quell the onslaught, only to find Bell Cranell standing in its way. Bell seeks to protect the rampaging monster behind him, but in order to do so, he'll have to go up against Aiz herself...