The series was heavily influenced by Japanese tokusatsu media, especially Ultraman, while the author's struggles in the manga industry served as a basis for the main character's backstory.

An anime television series adaptation produced by Production I.G aired from April to June 2024 with a second season set to premiere in July 2025.

Japan has the highest rate of kaiju attacks in the world, therefore in order to combat them it establishes the Japanese Anti-Kaiju Defense Force (JAKDF).

Defense Force officers wear powered suits made from kaiju remains that grant them increased strength, speed, and durability.

Kafka has failed the examination numerous times and works in a clean-up crew that disposes of kaiju remains after battle.

Kafka meets a young part-time worker in his company, Reno Ichikawa, an aspiring JAKDF member, who reignites his desire to enlist once again.

Kafka is, reluctantly, apprehended by Mina and sent to JAKDF headquarters where he is given a chance to prove his usefulness after he defeats the Director General of the Defense Force, and Kikoru's father, Isao Shinomiya, in a duel.

9 while the real one attacks Isao and absorbs him and his Numbers 2 weapon, a powered suit of armor created from the remains of Kaiju No.

Matsumoto had always loved tokusatsu, and he particularly liked the protagonist archetype seen often in the genre—where individuals gain extraordinary abilities, and become a hero, but also bear the weight of inner struggle as a consequence.

[34] Influenced by tokusatsu media such as the Ultraman series, specifically Ultraseven (1967), as well as Shin Godzilla (2016)[35] and Pacific Rim (2013),[30] Matsumoto aimed to create a story that follows a protagonist who has to achieve their goal while hiding their identity from a hostile organization they are also a part of, seeing it as an entertaining concept.

[35] The decision to have Kafka try to join Defense Force to fulfill his dreams was decided on early in the series' development although there were plans to have him maintain a secret identity while leading a normal life.

[40] Toho Animation producer Katsuhiro Takei said that Production I.G and studio Khara were brought on to the project due to similarities that Kaiju No.

8's focus on the daily lives of its characters was influenced by Production I.G's film Patlabor (1989) while the story's setting was reminiscent of Khara's Neon Genesis Evangelion (1995) series.

[42] Directors Tomomi Kamiya and Shigeyuki Miya would indicate which sequences required 3D animation during storyboarding[43] while Kimura and mechanical designer Shinobu Tsuneki worked closely with the team in order to evoke the aesthetics of previous Production I.G films such as Patlabor (1989) and Ghost in the Shell (1995) focusing on realistic depictions of military combat.

[42] Extensive 3D animation was used for portraying battles against large numbers of monsters and for dynamic camera movement in action sequences.

Directed by Hibiki Yoshizaki with Kouhei Nakama serving as CG director, the opening sequence aimed to show the origin of kaiju.

[53] Shueisha began publishing chapters of the series on its Manga Plus website and app on July 22, 2020, under the title Monster #8[54] in English and several other languages.

[55] To promote the release of the first volume in France, publisher Crunchyroll (then known as Kazé) displayed a mural on the Bibliothèque Nationale in Paris from October 6–15, 2021.

[56] The series is licensed in Italy by Star Comics, the publication of which was commemorated by the display of a mural in the Porta Genova metro station in Milan.

[57] The series is also licensed in Spain by Planeta Cómic,[58] in Argentina by Editorial Ivrea,[59] in Taiwan by Ever Glory Publishing,[60] and in Poland by Studio JG.

[74] On August 4, 2022, it was announced that the manga would be receiving an anime adaptation,[75][76] later revealed to be a television series produced by Production I.G, with Studio Khara supervising the kaiju designs and artworks.

Bandoh worked with various artists such as (sic)boy, Taiiku Okazaki and LEO Imai to compose original songs for the anime.

American artists Patrick Paige II of The Internet and Suni MF are also featured on the soundtrack which was released on June 26, 2024.

[91] Kafka Hibino is featured as a playable character in the video game Captain Velvet Meteor: The Jump+ Dimensions that was released on the Nintendo Switch on July 28, 2022.

[95] A life-size statue of Kafka's kaiju form was displayed at the Tachikawa Station on the Chūō Main Line from April 26–29, 2024.

[f] However, the first volume received some criticism for its formulaic beginning[141][151] as well as, what was deemed as, inconsistent art quality and fast pacing that sacrifices character development.

"[164] James Beckett complemented Production I.G for successfully balancing comedic elements of the story with "wonderful and weighty little beats that sell the entire world that much more effectively.

[164] Digital Spy's Janet A Leigh praised the series' premiere for its animation and action, comparing its premise to Attack on Titan but with a more light-hearted tone.

[165] Toussaint Egan of Polygon similarly described the series' premise as a combination of My Hero Academia and Pacific Rim while praising its tone, dramatic moments, action and art direction.

[174] Isaiah Colbert of IGN wrote positively of the first season saying that even though the series follows standard tropes of "other shōnen anime," its balance of action and drama allowed for "character-rich moments" that added depth and intrigue to the story.