On his way to a convenience store, Kazuya Shiina tries to defend two young girls from an armed assailant, only to end up getting stabbed himself and dying on the spot. This good deed allows him to be reborn with all his memories in another world as Cain von Silford, the third son of a margrave. When Cain turns five, a baptismal ceremony in the church grants him an audience to the seven gods who preside over the world. Not only do the gods fill him in on the circumstances of his reincarnation, but they also give Cain their respective divine protections—allowing him to use cheat-like abilities in swordsmanship, magic, and many other aspects. With these blessings, Cain sets out to live a fulfilling life that he deems a dream come true. However, it soon becomes clear that the gods have more plans for him than just a haphazard bestowal of overwhelming power.

Far to the north of the world lies Hell's Gate, a portal formerly used by the Demon Lord to invade the human realm. Thanks to the legendary hero Shion Bladearts, wielder of Excalibur, and his loyal band of companions, the Gate was sealed off and the demonic threat was vanquished. Unfortunately, the seal was incomplete and has begun to weaken, allowing the demons to once again begin their attack. Worried about the safety of his village, selfish and perverted farmer Touka Scott dig pitfalls to defend against the demons. But fear not, for Shion is on his way to reseal Hell's Gate and save humanity! Or at least he was, because the legendary hero is dead, having fallen into one of the pitfalls Touka dug. Luckily, dealing with the dead is the specialty of necromancer Anri Haynesworth. While she can't revive him, Anri can at least salvage their quest by forcing Touka's soul into Shion's rotting body and dragging him along to Hell's Gate in Shion's place. Not wanting to be left behind, Touka's childhood friend Yuna Yunis tags along. Together, the three of them set out as what just might be the most unsuitable party to ever try to save the world!

After surviving a brutal terrorist attack on Plant Quetta, Suletta Mercury returns to dueling at the Asticassia School of Technology, while Miorine Rembran sits at her injured father's side, waiting to see if he will recover. As the residents of Earth House are preoccupied with their respective troubles, two members of Dawn of Fold—the perpetrators of the attack—secretly infiltrate the school, putting Suletta and her friends at risk. At the same time, Prospera, Suletta's mother, approaches Miorine to propose the continuation of "Quiet Zero"—a project headed by Miorine's father that can allegedly end all war. Prospera seems to be another political figure with hidden, opposing motives, and whether she truly has Suletta's well-being at heart remains to be seen.

A powerful necromancer known as the Corpse God dies during a legendary battle, only to be reborn as Polka Shinoyama, a young boy in modern-day Tokyo. In the process of trying to adapt to his new physical body, he gets targeted by various groups that deal with the supernatural. Among them is Misaki Sakimiya, a high school girl who can see spirits and is out for his blood from the very moment they meet. Attempting to make sense of this situation where unknown parties want him dead, Polka eventually meets Takumi Kuruya, a contractor skilled in surveillance and hacking, and Lisa Kuraki, a crime boss operating out of Shinjuku. Alongside these—and other unexpected—allies, Polka braves danger to reveal the truth of his reincarnation and the fate awaiting the world he now lives in.