Kaiju No. 8

Kaiju No. 8 (Japanese: 怪獣8号, Hepburn: Kaijū Hachigō), also known in English as Monster #8, is a Japanese manga series written and illustrated by Naoya Matsumoto. It has been serialized on Shueisha's Shōnen Jump+ online platform since July 2020, with its chapters collected in 15 tankōbon volumes as of March 2025. Shueisha has also published the series digitally on its Manga Plus platform in English and several other languages. Viz Media began publishing the series digitally in August 2020 and has published the series in print in North America since December 2021.
The story follows Kafka Hibino who, after ingesting a parasitic creature, gains the ability to turn into a kaiju and now must navigate using his power while trying to become part of an organization that eliminates kaiju to fulfill a promise he made with a childhood friend. Matsumoto wrote the outline of the story of Kaiju No. 8 near the end of 2018 making it his second series for the magazine. 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. The series has spawned a light novel, two spin-off manga series, and an upcoming video game.
By March 2025, the manga had over 18 million copies in circulation. The series has been praised for its premise, characters, and art. The series won the Next Manga Award in the web manga category in 2021 and was nominated for the Eisner Award in 2022.
Kaiju No. 8 is set in a world in which monsters named kaiju regularly cause disasters. 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). Kaiju are assigned a "fortitude level"—a scale indicating their overall strength, and are classified as honju—more dangerous, stronger kaiju, and yoju—smaller kaiju that can accompany or sprout off from honju. Kaiju that have high fortitude levels or abnormal characteristics are given a number as an identifier based on when they first appear, and are classified as daikaiju.
Defense Force officers wear powered suits made from kaiju remains that grant them increased strength, speed, and durability. The suits have a total power output, measured in the form of a percentage (referred to as "unleashed combat power"), which varies from person to person (depending on their ability), with a maximum of 100%. The suits also influence how strong an officer's weapons are.
Daikaiju remains are used to create stronger weapons named Numbers (ナンバーズ, Nanbāzu) that are named after the daikaiju they are made from, but only a select few can use them if they are deemed compatible. Numbers weapons are much stronger than regular suits and provide their users with special abilities. The Defense Force consists of field officers led by platoon leaders, with varying levels of unleashed combat power, and captains and vice-captains whose combat power exceeds 90% and who lead divisions. Field officers are supported by a team of operators who provide information on kaiju, and monitor the field officers' health and suit output.
After their town is destroyed by kaiju, childhood friends Kafka Hibino and Mina Ashiro both vow to become members of the Japanese Anti-Kaiju Defense Force (JAKDF) to fight kaiju together. Mina has since become the captain of the JAKDF's 3rd Division and is valued due to an ability that makes her shots highly destructive. 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. However, a parasitic creature enters Kafka's body through his mouth and he gains the ability to turn into a humanoid kaiju. After escaping from the JAKDF, Kafka is given the code name "Kaiju No. 8" and decides to apply while keeping his kaiju form a secret.
Kafka and Reno pass the exam and join the 3rd Division along with Kikoru Shinomiya, a kaiju-slaying prodigy who Kafka saved during the test from another humanoid kaiju which the JAKDF names "Kaiju No. 9." Kafka encounters No. 9 once more when it tries to kill Reno during their first mission with the 3rd Division. Kafka fails to kill No. 9 and, as he tries to hide, he is attacked by the vice captain of the 3rd Division, Soshiro Hoshina. After a short fight, Kafka escapes from the vice captain, still maintaining his cover. Kafka is eventually forced to reveal his kaiju form when he transforms to save the 3rd Division's Tachikawa base from destruction after it is attacked by a third humanoid kaiju named Kaiju No. 10.
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. Kafka and Kikoru join the 1st Division led by captain Gen Narumi where they again fight No. 9 who attacks Shinagawa. They kill two versions of No. 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. 2, making No. 9 stronger in the process. No. 9 escapes and prepares for an invasion of Japan while Kafka and Kikoru train for the invasion, with Kikoru gaining her mother's Numbers 4 weapon. Reno gains the Numbers 6 weapon and trains with the 4th Division. While Kafka trains with Soshiro at an old shrine commemorating kaiju slayers of the Meireki era, he notices a specter of an old kaiju slayer.
Several months later, No. 9 begins its invasion of Japan, sending a group of kaiju identified as Kaiju Nos. 11–15 that attack Gen, Soshiro, Kafka, Mina and Kikoru respectively. After some struggle, Gen, Soshiro, Kafka, and Kikoru succeed in defeating their opponents with Mina being the last one to defeat hers. However, No. 9 uses the corpse of Kaiju No. 14 as a portal to close the distance between itself and Mina, revealing its plan to kill and absorb Mina in order for it to gain her highly destructive ability. Kafka manages to reach Mina in time with the timely arrival of Reno who clears a path for him. Kafka and Mina succeed in defeating No. 9, however No. 9 mortally wounds Kafka and reveals to him that it absorbed an old and powerful kaiju of the Meireki era that devastated Japan in the past who proceeds to take over No. 9's body.
Naoya Matsumoto began his career in 2006 with Neko Romancer, a series that was published in Jump Giga (then known as Akamaru Jump). He authored a series titled Nekowappa! that debuted in Shueisha's Weekly Shōnen Jump in 2009. The series was a continuation of a one-shot that Matsumoto wrote for the JG1 One-Shot festival. He published another one-shot titled Shikai Enbu in the 2012 spring edition of Jump Giga (then known as Jump Next) before starting his second serialization with Pochi Kuro that debuted on Shueisha's Shōnen Jump+ application and website in 2014.
Matsumoto presented the idea and general outline of Kaiju No. 8's story to deputy editor-in-chief of Shōnen Jump+, Seijiro Nakaji, near the end of 2018. Influenced by tokusatsu media such as the Ultraman series, specifically Ultraseven (1967), as well as Shin Godzilla (2016) and Pacific Rim (2013), 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. 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. Kafka's predicament in the series was partly inspired by Matsumoto's career struggles in the manga industry. Working on Kaiju No. 8 was challenging for Matsumoto but it allowed him to move away from his usual stories which was echoed by Nakaji who said that the idea behind the series was unexpected since Matsumoto had usually authored fantasy stories.
Page layouts are designed to be easy to follow especially on smartphones due to the manga being released digitally. Nakaji said that they try to take advantage of the series being digital by giving an example of a panel in the second chapter that was completely in color, something that would not be possible if the series was being published in a physical magazine. The codenames that are given to kaiju were inspired by typhoon categorization on the suggestion of a coworker of Matsumoto's who pointed out that this would make the kaiju appear more as disasters. The kaiju designs are inspired by mythological creatures, animals, and plants. Kaiju No. 8's design was modeled after depictions of oni while the design's color was inspired by the film Tron (1982).
Matsumoto works with three assistants for the series: Osamu Koiwai who is responsible for background art, Jiro Sakura who does "finishing work" and Mantohihi Binta who is credited for weapon design. For background art, Matsumoto prepares a storyboard providing panel compositions of a chapter that are sent to Koiwai who creates an initial draft for Matsumoto's approval. Upon approval, Koiwai can proceed with creating the final version of the background art which takes 3–4 days to complete. Koiwai shares his creative process for the series on YouTube.
Tetsuya Nishio was brought onto the project as character designer and chief animation director by Production I.G producer Masashi Ohira who thought that Nishio's designs facilitate animation, and while not as detailed, still had a "three-dimensional feel." Nishio provided designs for human characters and humanoid kaiju that are present in the story. Apart from serving as chief designer of kaiju for the series, Mahiro Maeda provided detailed imagery of kaiju anatomy during battle scenes. Ohira approached Shinji Kimura to serve as art director as they thought that Kimura could create a sense of realism in the setting. 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 had to previous works of both studios. Specifically, Takei thought 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. By including both studios in the production process Takei said that they aimed to recreate the look of anime from the 1990s.
The anime utilizes a mix of hand-drawn and 3D animation. The lead director of 3D animation, Masaru Matsumoto, worked with a small team of animators that utilized Autodesk 3ds Max and Blender software with production starting in March 2022 and continuing while the series was airing. Directors Tomomi Kamiya and Shigeyuki Miya would indicate which sequences required 3D animation during storyboarding 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. Extensive 3D animation was used for portraying battles against large numbers of monsters and for dynamic camera movement in action sequences. The opening sequence of the first season was produced by studio Khara in collaboration with Japanese creative agency WOW. Directed by Hibiki Yoshizaki with Kouhei Nakama serving as CG director, the opening sequence aimed to show the origin of kaiju.
Written and illustrated by Naoya Matsumoto, Kaiju No. 8 started on Shueisha's Shōnen Jump+ application and website on July 3, 2020. In August 2020, Matsumoto and Kaiju No. 8 adopted a schedule where a new chapter is published every week for three weeks, followed by a one week break. From June 25, 2021, a new schedule was adopted where a new chapter is published every two weeks. Shueisha has collected its chapters into individual tankōbon volumes. The first volume was released on December 4, 2020; a promotional video for the volume, presented as a news program, was shown on the big screen of Yunika Vision at Seibu-Shinjuku Station from December 4–10, 2020. As of March 4, 2025, 15 volumes have been released.
Viz Media began publishing the series in English on its website on August 2, 2020, under the title Kaiju No. 8, and on February 19, 2021, it announced that it had licensed the series for print in English, releasing the first volume on December 7, 2021. Shueisha began publishing chapters of the series on its Manga Plus website and app on July 22, 2020, under the title Monster #8 in English and several other languages. On March 30, 2023, Manga Plus announced that it would include Kaiju No. 8 in the title of the version of the manga on its service.
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. 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. The series is also licensed in Spain by Planeta Cómic, in Argentina by Editorial Ivrea, in Taiwan by Ever Glory Publishing, and in Poland by Studio JG.
A spin-off manga illustrated by Kentaro Hidano, titled Kaiju No. 8: B-Side (怪獣8号 side B) ran from January 5 to July 12, 2024, on Shōnen Jump+. The spin-off is based on the light novel Kaiju No. 8: Exclusive on the Third Division, written by Keiji Andō, and features side-stories of Defense Force members. Shueisha collected its chapters in two tankōbon volumes, released on April 4 and October 4, 2024.
Shueisha and Viz Media began publishing the series in English on January 4, 2024, Shueisha on its Manga Plus website and app and Viz Media on its Shonen Jump website and app. Viz Media will release the volumes in print, with the first one set to be released in Q2 2025.
Another spin-off manga, illustrated by Kizuku Watanabe [ja], titled Kaiju No. 8 Relax, began its serialization in Saikyō Jump on June 4, 2024, and on Shōnen Jump+ on June 7 of the same year. Viz Media will be publishing the series in print, with the first volume set to be released in Q3 2025.
A 4-chapter side-story light novel titled Kaiju No. 8: Exclusive on the Third Division (怪獣8号 密着！第3部隊, Kaijū Hachigō: Mitchaku! Daisan Butai) written by Keiji Andō and illustrated by Matsumoto, was released on November 4, 2022. On February 2, 2024, Viz Media announced that it had licensed the light novel for print in English. It was published on December 3, 2024.
On August 4, 2022, it was announced that the manga would be receiving an anime adaptation, later revealed to be a television series produced by Production I.G, with Studio Khara supervising the kaiju designs and artworks. It is directed by Shigeyuki Miya and Tomomi Kamiya, with scripts by Ichirō Ōkouchi, character designs and chief animation direction by Tetsuya Nishio, art direction by Shinji Kimura [ja] and monster designs by Mahiro Maeda. The series aired from April 13 to June 29, 2024, on TV Tokyo and its affiliates, alongside Twitter for simulcast in Japan.
Crunchyroll streamed the series as it aired in Japan, as well as dubbed versions an hour after its television premiere, which includes English, Brazilian Portuguese, French, German, Italian, Spanish, Latin American Spanish, Hindi, Telugu, and Tamil. Medialink licensed the series for streaming in Southeast Asia on its Ani-One Asia YouTube channel.
After the airing of the final episode, a sequel was announced. It was announced that it will be a second season set to premiere in July 2025. A compilation film of the first season and an original episode, "Hoshina's Day Off" (保科の休日, Hoshina no Kyūjitsu), was screened together in Japanese theaters for three weeks starting on March 28, 2025. It was announced that film would have a worldwide release, later revealed to be screenings in North America the United Kingdom and Ireland with distribution by Sony Pictures Entertainment and under the title "Kaiju No. 8: Mission Recon". The film will also be released in India. Crunchyroll will stream the second season.
A series of short episodes, titled Minute! Kaiju No. 8 (ミニっと！かいじゅう8号, Minitto! Kaijū 8-gō), started on Toho Animation's YouTube channel on December 6, 2024.
The music was composed by Yuta Bandoh creating a film score for the series. Bandoh worked with various artists such as (sic)boy, Taiiku Okazaki and LEO Imai to compose original songs for the anime. The soundtrack also features music by "The Kaiju Band", a musical project created for the anime consisting of guitarist Takayuki "Kojiro" Sasaki, King Gnu bassist Kazuki Arai and drummer Shun Ishikawa. American artists Patrick Paige II of The Internet and Suni MF are also featured on the soundtrack which was released on June 26, 2024. The opening theme song for the first season is "Abyss", performed by Yungblud, while the ending theme song is "Nobody", performed by OneRepublic. The ending theme song for the "Hoshina's Day Off" original episode is "Invincible", performed by OneRepublic.
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.
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. Kafka's voice actor Masaya Fukunishi was appointed as the ceremonial one-day manager at the Kaiju No. 8 store in the station. The statue was displayed in four other places from May 1 to June 16, 2024.
A video game project, tentatively titled Kaiju No. 8: The Game, was announced in June 2024. It is developed by Akatsuki Games and is set to be available for smartphones and Windows (via Steam).
According to Yūta Momiyama, the deputy editor-in-chief of Shōnen Jump+, Kaiju No. 8, along with Spy × Family, have been very popular and are doing especially well on the Manga Plus service. In December 2020, it was reported that Kaiju No. 8 surpassed 30 million views, making it the fastest Shōnen Jump+ series to achieve this feat, and each new chapter published surpasses one million views. In February 2021, the series reached 70 million views. In April 2021, the series reached over 100 million views. In February 2023, the series reached 400 million views. The series ranked tenth on AnimeJapan's 5th "Most Wanted Anime Adaptation" poll in 2022.
The School Library Journal listed the first volume of Kaiju No. 8 as one of the top 10 manga of 2021. It ranked third on Takarajimasha's Kono Manga ga Sugoi! 2022 list of best manga for male readers. The series ranked second on the Nationwide Bookstore Employees' Recommended Comics of 2022. The series was included in Polygon's list of the best comics of 2021, Kotaku's list of the 11 best manga series of 2021 and The Fandom Post's list of the 12 best manga series of 2020.
The series' first volume sold 90,831 copies in its first week, and 69,404 copies in its second week. By December 2020, the first volumes had over 430,000 copies in circulation (print and digital). In January 2021, it was reported that the series was the best-selling new manga of 2020, within only 28 days since the first volume was published. By March 2021, the manga had over 1 million copies printed physically and 200,000 copies sold digitally, making it the fastest Shōnen Jump+ series to reach 1 million copies in circulation, and 20 days later reached 1.5 million copies in circulation. By June 2021, the manga had 2.5 million copies in circulation, and by middle of the month it reached 3 million copies. By September 2021, the manga had over 4 million copies in circulation; over 5.5 million copies in circulation by December 2021; over 6.7 million copies in circulation by March 2022; over 7.8 million copies in circulation by July 2022; over 8 million copies in circulation by August 2022; over 10 million copies in circulation by December 2022; over 11 million copies in circulation by March 2023; over 13 million copies in circulation by April 2024; over 14 million copies in circulation by June 2024; over 15 million copies in circulation by July 2024; over 16 million copies in circulation by September 2024; and over 18 million copies in circulation.
The series' fifth and sixth volumes were among the 30 best-selling manga volumes of 2022. The ninth volume was among the best-selling manga volumes of 2023. Volume 10 was Shueisha's seventh highest first print run manga volume of 2023–2024 (period from April 2023–March 2024), with 600,000 copies printed.
In the United States, individual volumes have ranked on Circana (formerly NPD) Bookscan's monthly list since 2021 and on The New York Times' Graphic Books and Manga bestseller monthly list since 2022. The series' first volume sold sold 118,000 copies in 2022, and the fifth one sold 52,000 copies in 2023.
In France, the series sold 22,041 copies in its first week, making it the best-selling debut of manga in France. By April 2023, the series sold 888,888 copies in France. In Italy, the first volume had a first print run of 245,000 copies (including various editions), surpassing Demon Slayer: Kimetsu no Yaiba, which has 200,000 copies in circulation per volume.
The series' first volume has been positively received. The series has been praised for its premise, which has drawn comparisons to the Ultraman series, for its art, particularly the kaiju designs and for its comedy. Kafka Hibino has been singled out as an endearing character and a novel aspect of the series due to his age. However, the first volume received some criticism for its formulaic beginning as well as, what was deemed as, inconsistent art quality and fast pacing that sacrifices character development.
The series premiere was positively received. In a series of positive reviews for Anime News Network, Rebecca Silverman praised the art, animation and music saying that the series treads familiar territory but that "it's very comfortably working within the bounds of its genre and having fun with them." 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." Nicholas Dupree praised the show's action sequences and worldbuilding, noting that Kafka is a character who is easy to root for while Richard Eisenbeis praised the animation, specifically the detailed and realistic depiction of kaiju fights and their dissection, although he found the character designs to be simplistic. 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. 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.
Grant Jones of Anime News Network wrote positively about the first season with high praise for the season's second half. Episode 6 ("Sagamihara Neutralization Operation at Daybreak") provided story elements that expanded upon the world of the series. Episode 8 ("Welcome to the Defense Force") was a highlight due to a well animated fight scene between Kafka and Soshiro, for providing depth to supporting characters and for increased tension due to Kafka's secret identity nearly being revealed. Episode 10 ("Secret Revealed") was praised for the surprising development of Kafka revealing his kaiju form to the Defense Force as Jones expected this to happen much later. The final two episodes were praised for their overall presentation in terms of animation, direction and storyboarding with the eleventh episode ("Kaiju No. 8 Captured") bringing the "visual fidelity to the highest levels in the season thus far" while the final episode ("Kafka Hibino") provided an effective cliffhanger for the second season. Criticisms of the season were aimed at the character designs which were described as "rather bland" and "very flat." Episode 3 ("Revenge Match") was seen as a low point of the season due to its reliance on tropes and its "lackluster" animation. 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.