The Hidden Dungeon Only I Can Enter (Light Novel) Vol. 4

Noir needs to make the most of the last days of summer. A letter from his older brother Gillan, studying to be a merchant in a neighboring kingdom, gives him the perfect idea: road trip! Accompanied by his friends, Noir heads to the town of Honest. But when they arrive, they find a city besieged by monsters! Noir's peaceful summer vacation is about to get way more exciting than he bargained for!