The first episode of "season" one was pre-aired on the Fate Project New Year's Eve TV Special 2020 program.

The story takes place in Nikko city, Tochigi Prefecture, where girls aim for the top of the world through ice hockey. Local junior high school student Manaka and her younger sister Ayaka, whom she forcibly invited, hit the gate of first-hand experience with ice hockey, held by the Nikko-based team Dream Monkeys. The two are joined by their childhood friends Kaoruko and Mami. As the girls practice, they become fascinated with ice hockey and eventually join the team.

In an unexpected turn of events, dull high school student Hiro Yuuki obtains the full dive role-playing game Kiwame Quest. Created by the best of technology, the game claims to take "reality to its extremes," from stunning graphics, NPCs' behavior, to the scent of vegetation, and even the sensation of wind brushing against the skin—everything was the result of an ultimate workmanship. Except, the game is a little too realistic and messy to clear. Kiwame Quest features over ten quadrillion flags and reflects the players' real-life physical abilities in the game. Being hit in the game also hurts in real life and slash wounds take days to heal. The only reward here is the sense of accomplishment. Conquer the most stressful game in history that can't be played casually! (Source: MAL News)

Denji is robbed of a normal teenage life, left with nothing but his deadbeat father's overwhelming debt. His only companion is his pet, the chainsaw devil Pochita, with whom he slays devils for money that inevitably ends up in the yakuza's pockets. All Denji can do is dream of a good, simple life: one with delicious food and a beautiful girlfriend by his side. But an act of greedy betrayal by the yakuza leads to Denji's brutal, untimely death, crushing all hope of him ever achieving happiness. Remarkably, an old contract allows Pochita to merge with the deceased Denji and bestow devil powers on him, changing him into a hybrid able to transform his body parts into chainsaws. Because Denji's new abilities pose a significant risk to society, the Public Safety Bureau's elite devil hunter Makima takes him in, letting him live as long as he obeys her command. Guided by the promise of a content life alongside an attractive woman, Denji devotes everything and fights with all his might to make his naive dreams a reality.