Polka Shinoyama's life takes a dramatic turn after being forced to use his magical powers in public. His divination cabinet attracts the attention of several people hellbent on exposing his true nature as the reincarnation of Corpse God, a necromancer from the Other World. To make matters worse, Polka and his friends are framed for the murder of one of their protector's employees. When group member Takumi Kuruya is abducted by his former boss, Kuon Higuro, Polka sends his most trustworthy ally Misaki Sakimiya to their friend's rescue. It turns out that some of the recent incidents the group finds themselves caught up in are interconnected, and Polka needs to be twice as careful if he wants to make it out alive from this maze of pitfalls.

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.

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.

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.