Loner Life in Another World Vol. 4 (manga)

FIRING ON ALL FOUR CYLINDERS! Haruka reluctantly saves the day again and again, but now he wants nothing more than to go home to his cave and enjoy his loner life! But fate has grander designs in store for the hapless young lad. Word of an ancient, loot-laden dungeon rolls in, and the tantalizing allure of treasures unknown is too much for him to resist! Into the depths our loner hero goes, but he may well meet his match in the form of a being far more lonesome than he... The Dungeon Emperor!