Shidou Itsuka faces greater peril than ever due to his continued involvement with Ratatoskr. He has already sealed 10 Spirits, and Isaac Westcott, leader of Deus Ex Machina Industries, has finally decided to kill Shidou and plunder the Spirits' powers for himself. To achieve his goal, Isaac declares an all-out war against Ratatoskr, forcing the organization to exhaust its resources to ensure Shidou's survival. Despite being severely outnumbered and outmatched, a glimmer of hope exists in the form of the Spirit of Time, Kurumi Tokisaki. Shidou must seal and acquire Kurumi's power to travel to the past and confront the Spirit of Origin—the catalyst that started it all.

Hiroto Shinohara is a new transfer student to Academy Island, where games determine student rankings. The more games won, the more stars a student has, with the highest ranking being that of a Seven Star. On Hiroto's first day, he accidentally antagonizes Sarasa Saionji, the so-called Empress of Academy Island and granddaughter of the island's head director. Forced into a game fueled by misunderstandings that he somehow ends up winning, he is thrust into a major bluff where he must lie about his ranking or risk expulsion from the school and island. Fortunately, with the help of the mysterious Company headed by Shirayuki Himeji, Hiroto is not alone in his bluff. The Company will do everything in its power to help him cheat his way through the game challenges sent his way by students wanting to beat him. Though he is a One Star student, he must fight as though he is actually a Seven Star, and overcome insurmountable odds in his quest to search for a missing girl from his past.

Veteran adventurer Nick, mage Tiana, cleric Zem, and half-dragon Curran each show up alone at a tavern, only to find themselves seated at the same table. As the night goes on, they take turns divulging their grievances and the hobbies they have taken up as a means of coping. While their stories are utterly different, there is one common thread: betrayal. Each of the four, having been bitterly betrayed by someone they treasured, has developed a deep-seated distrust of humanity. But in addition to their similar worldviews, the four have one more commonality: a critical lack of funds. Realizing that things cannot continue as they are, they decide to form a party, rank up, and make as much money as possible to spend on their respective hobbies. What these disillusioned adventurers do not know, however, is that they will one day save the world from unfathomable peril.

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.