Fifteen years have passed since the war between humans and demons began. Dissatisfied with their slow advance into the Demon Realm, the Hero abandons his companions to quickly forge ahead towards the Demon Queen's castle. Upon his arrival at the royal abode, the Hero makes a startling discovery: not only is the Demon Queen a woman of unparalleled beauty, but she also seeks the Hero's help. Confused by this unexpected turn of events, the Hero refuses to ally himself with his enemy, claiming that the war the demons have waged is tearing the Southern Nations apart. However, the Demon Queen rebuts, arguing that the war has not only united humanity but has also brought them wealth and prosperity, providing evidence to support her claims. Furthermore, she explains that if the war were to end, the supplies sent by the Central Nations in aid to the Southern Nations would cease, leaving hundreds of thousands to starve. Fortunately, she offers the Hero a way to end the war while bringing hope not only to the Southern Nations, but also to the rest of the world, though she will need his assistance to make this a reality. Finally convinced, the Hero agrees to join his now former enemy in her quest. Vowing to stay together through sickness and health, they set off for the human world. [Written by MAL Rewrite]

As a child living in the town of Lawless, Angelo Lagusa has witnessed a tragedy: his parents and younger brother have been mercilessly slaughtered by the Vanetti mafia family. Losing everything he holds dear, he leaves both his name and hometown behind, adopting the new identity of Avilio Bruno. Seven years later, Avilio finally has his chance for revenge when he receives a mysterious letter prompting him to return to Lawless. Obliging, he soon encounters the Vanetti don's son, Nero, and seeks to befriend him using the skills he has quietly honed for years. Set during the Prohibition era, 91 Days tells the story of Avilio's dark, bloodstained path to vengeance, as he slowly ends each of the men involved in the killing of his family. [Written by MAL Rewrite]

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.

Amatsuyu "Jouro" Kisaragi is a completely average second-year high school student who has two dates over one weekend⁠—with the student council president Sakura "Cosmos" Akino on Saturday, then with his childhood friend Aoi "Himawari" Hinata on Sunday. Sadly for Jouro, both girls proclaim their love for his best friend Taiyou "Sun-chan" Ooga, the ace of the baseball team. Accepting each of their requests for advice and guidance, he is now responsible for helping the two girls win the heart of the same guy. Unbeknownst to his friends, Jouro's friendly and obtuse image is all but a ruse designed to cast himself as the clueless protagonist of a textbook romantic comedy. A schemer under his cheery facade, he makes the best of this unexpected turn of events with a new plan: get Sun-chan to fall for either Cosmos or Himawari and take the other as his own prize. But Jouro's last-ditch effort is threatened by the gloomy, four-eyed Sumireko "Pansy" Sanshokuin, who surprises Jouro with not only her knowledge of his secret personality but also a confession to the true self he hid for all this time. Stuck in this hilariously messy situation, each of the five students must navigate countless lies, traps, and misunderstandings to come out on top. [Written by MAL Rewrite]