It is not strange that the Demon Lord's forces fear the Crimson Demons, the clan from which Megumin and Yunyun originate. Even if the Demon Lord's generals attack their village, the Crimson Demons can just easily brush them off with their supreme mastery of advanced and overpowered magic.

When Yunyun receives a seemingly serious letter regarding a potential disaster coming to her hometown, she immediately informs Kazuma Satou and the rest of his party. After a series of wacky misunderstandings, it turns out to be a mere prank by her fellow demon who wants to be an author. Even so, Megumin becomes worried about her family and sets out toward the Crimson Demons' village with the gang.

There, Kazuma and the others decide to sightsee the wonders of Megumin's birthplace. However, they soon come to realize that the nonsense threat they received might have been more than just a joke.

Kazuma meets a novice adventurer called Ran who claims to be Kazuma's fan. A quest is proposed to Kazuma and his party in front of Ran, so he accepts the quest to look good in front of his fan; after some convincing, they all go to fight the metal golem.

After fending off the threat of a Neuroi invasion of Romagna and destroying the enemy's nest over Venezia, Yoshika Miyafuji goes back to her home town in the Empire of Fusou. Despite the loss of her magical and healing abilities, the former officer of the 501st Joint Fighter Wing wants to continue studying medicine. This is in order to help those in need, both civilians and those on the front lines alike. She receives an invitation from a prestigious school in Europe and decides to accept the offer, embarking on a journey back to the war-torn continent. However, a new danger arises, as more and more Neuroi manage to break through human defense lines, appearing unnoticed in supposedly safe areas and disturbing the balance of power in Europe. Yoshiki's sense of duty collides with her inability to pilot a Striker Unit, but with her friends in peril, it seems that there is only one thing she can do.

The story takes place shortly before Cartaphilus took a nap and Chise became an auditor at the academy. Elias and his friends help Chise prepare for the academy, where in the middle of everyday life, Spriggan visits the mansion on a spooky horse with the words, "The appearance of the ghost hunting association is unusual this time." Gabriel, an ordinary boy who just moved from London, was bored of his environment of parting with friends, being in an unfamiliar location, and everything else. Sitting by the window and glancing beyond, he spotted a purple smoke and decided to chase after it, looking to escape his boredom. Though it should not, the world of the boy begins to converge with the wizards, who live on the other side behind a thick veil.