With debt looming over her, Aqua convinces Kazuma to accept a high difficulty quest to purify a lake, which doesn't require killing any monsters.

Darkness, Aqua, and Megumin are back to continue their quest against the Devil King. Kazuma is back too, but the only adventures he has waiting for him exist within the criminal justice system.

Kazuma's incorrigible ego forces him and his unmotivated idiosyncratic party to accept quest after dangerous quest following his bragging in front of his first hardcore fan. This time, the adventurer's guild requests that they take out a giant golem guarding ancient ruins...

Kazuma thinks of a way to stay in the capital for Iris's sake, and declares that he will capture the thief who's causing a stir in the streets! Since the thief targets nobles with bad behavior, Kazuma and his friends decide to stay at Alderp's mansion.

The Devil King's army attack alarm rings in the royal capital! The adventurer's guild calls on high-level adventurers to join the battle. Having failed to capture the thief at Alderp's mansion, Kazuma joins the fight in order to redeem his reputation.