After Masakazu Ishiguro ended And Yet the Town Moves, he spent around a year devising a new series. Ishiguro was inspired by the early Kojiki era of Japan, and relationships between humans and artificial intelligence when planning to write Heavenly Delusion. The original concept was devised in 2013 as concept art for the cover of the magazine Monthly Comic Ryū (2013). There were unintentional similarities to Ishiguro's favorite work, Akira, such as the post-apocalyptic setting, and the dynamic between Maru and Kiruko. Ishiguro decided to keep drawing the manga like Akira, paying close attention to the backgrounds and the way the leads try eating. Ishiguro aimed to properly write "evil" in contrast to And Yet the Town Moves, so the post-apocalyptic world of Heavenly Delusion is far darker than his previous works'.

After drawing sketches of young characters suitable for the shōnen manga demographic, editorial members from Afternoon asked Ishiguro to write for their seinen magazine again. In contrast to And Yet the Town Moves, Heavenly Delusion employs a dark tone, specifically children's delusions. He still wanted returning fans to read Heavenly Delusion. One of the child charecters, Tokio, lives in a mysterious facility, and enjoys and collects fantasy paintings her friend Kona creates. Kona can imagine things he had never seen before; this aspect overlaps with Ishiguro's statement he is drawing delusions. At the end of the first volume, many of the plot threads have been laid out but to maintain the mystery theme, a few events are directly foreshadowed.

Ishiguro devised the manga when he was a university student. The story is based on the story of a race on a circuit; the Earth is destroyed in the middle of the race and the main character is about to die. For the title, Ishiguro wanted to use wordplay to create ambiguity. The Japanese characters of Heaven where use to connect with "Hell" in the title. Ishiguro claims his artwork became more detailed, most notably Kiruko's facial expression. Once reaching its ending, Ishiguro planned whether to make the title explicit. The man-eaters, kaiju-like creatures Maru and Kiruko fight, are based on prehistoric creatures such as Cambrian-period organisms; their shapes are often designed to appeal to Ishiguro's drawing style. He had been drawing science fiction themes since his childhood and continues exploring them in Heavenly Delusion; they were influenced by the late manga duo Fujiko Fujio.

Ishiguro thought about the manga for years. Because he enjoyed walking, he often fantasized about a world that had been destroyed by a catastrophe and found himself inspired by an anime in which the main character wandered alone, like Chirico from Armored Trooper Votoms. He liked the idea of a …

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Heavenly Delusion is written and illustrated by Masakazu Ishiguro, and it has been serialized in Kodansha's seinen manga magazine Monthly Afternoon since January 25, 2018. Kodansha has published its chapters in individual tankōbon volumes, the first of which was released on July 23, 2018; a promotional video that was directed by Tasuku Watanabe for the first volume was released on the same date. As of October 22, 2024, 11 volumes have been released.

In North America, the series is licensed in English by Denpa. The first volume was released on December 31, 2019.
A 13-episode anime television series adaptation by Production I.G was aired from April 1 to June 24, 2023, on Tokyo MX and other networks.
An official guidebook for Heavenly Delusion was released on November 22, 2022. It includes detailed information about the series' setting, story, characters, and features an interview with Ishiguro.

By December 2018, over 130,000 copies of the Heavenly Delusion manga were in circulation.

Reviewing the first volume of Heavenly Delusion, Anime News Network praised the narrative for its focus on Kiruko's and Maru's appealing relationship, and Ishiguro's character designs. The reviewer said while the volume explores the mysteries behind Kiruko, there were still too many mysteries the plot would explore in the future. The French website Manga News called the manga's premise captivating due to the mysteries it shows. Sigue en Serie also commented on the mysteries of the series, which would motivate readers to quickly move to the next volume to understand more of the plot through the parallel storylines. By the third volume, Manga News noted the events on the both storylines had been connected, especially from Tokio's point of view ,while the duo's journey was noted to be more comic than tragic as a result of the way Ishiguro writes the chapters. The reviewer still felt both plots offer interesting mysteries whose connections are not easily given away. Brutus magazine listed Heavenly Delusion on its list of "Most Dangerous Manga", which includes works with the most-stimulating and thought-provoking themes.

Makoto Yukimura, author of the manga Vinland Saga, expressed interest in the themes of Heavenly Delusion due to the idea of a heaven, as well as the way Ishiguro tells two connected stories at the same time.
Heavenly Delusion was ranked first on Takarajimasha's Kono Manga ga Sugoi! 2019 ranking of Top 20 manga series for male readers. Heavenly Delusion was one of the Jury Recommended Works at the 24th and 25th Japan Media Arts Festival in 2021 and 2022, respectively. The manga was awarded the French Daruma Award for the Best Screenplay category at the Japan Expo Awards in 2023.