After 2,000 years of countless wars and strife, the demon king Anos Voldigoad made a deal with the human hero, Kanon, to sacrifice his own life to ensure peace could flourish.

Finding that magic as a whole has begun to decline and his descendants weaker as a result of the peace he created, Anos, now technically a hybrid himself, decides to reclaim his former title.

[3] It was later acquired by ASCII Media Works, who published the first volume as a light novel under their Dengeki Bunko imprint in March 2018.

[62] On July 10, 2021, it was announced that the manga adaptation was cancelled due to Kayaharuka's illness as it was previously claimed they were undergoing treatment.

[64] An anime television series adaptation was announced at the "Dengeki Bunko Aki no Namahōsō Festival" event on October 6, 2019.

[3] The anime was originally set to premiere in April 2020, but it was delayed until July 2020 due to production complications resulting from the COVID-19 pandemic.

[73] The series was animated by Silver Link and directed by Masafumi Tamura, with Shin Oonuma serving as chief director.

[74] Jin Tanaka handled the series composition, while Kazuyuki Yamayoshi designed the characters, and Keiji Inai composed the music.