Gamer Kazuma dies in a freak accident, and is met in the afterlife by a crass goddess, Aqua.

It's great for Kazuma that he brought Aqua along with him, but unlike in a game world, much is missing from his adventurer's lifestyle. No money, no equipment, and even fighting the lowest ranking monsters is a hard-fought battle. That's when they decide to recruit new party members.

All of the weak monsters have gone into hiding since a leader of the devil king's army has settled in near town. Kazuma, who had been focusing on improving his skills, is stuck at a standstill. With nothing else to do, Kazuma tags along with Megumin's training, which consists of unleashing explosion magic into an abandoned castle.

The rampaging ancient weapon: the mobile fortress, Destroyer, is headed straight for Kazuma and party's city!

Vanir gives Kazuma the choice of either selling the intellectual rights for his real world products for a one-off payment of 300 million eris, or maintaining a profit-sharing contract of 1 million eris a month.