Kaiju No. 8 (Japanese:怪獣8号,Hepburn:Kaijū Hachigō), also known in English asMonster #8, is a Japanesewebmanga series written and illustrated byNaoya Matsumoto. It was serialized onShueisha'sShōnen Jump+ app and website from July 2020 to July 2025, with its chapters collected in 16tankōbon volumes. Shueisha has also published the series digitally on itsManga 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 akaiju 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 ofKaiju No. 8 near the end of 2018 making it his second series for the magazine. The series was heavily influenced by Japanesetokusatsu media, especiallyUltraman, while the author's struggles in the manga industry served as a basis for the main character'sbackstory.
Ananime television series adaptation produced byProduction I.G aired from April to June 2024, with a second season aired from July to September 2025. A "conclusion arc" to the anime series has been announced. The series has spawned alight novel, twospin-off manga series, and a video game.
By September 2025, the manga had over 19 million copies in circulation. The series has been praised for its premise, characters, and art. The series won theNext Manga Award in the web manga category in 2021 and was nominated for theEisner Award in 2022.
Kaiju No. 8 is set in a world in which monsters namedkaiju regularly cause disasters. Japan has the highest rate of kaiju attacks in the world, therefore in order to combat them it establishes theJapanese Anti-Kaiju Defense Force (JAKDF).[a] Kaiju are assigned a "fortitude level"—a scale indicating their overall strength, and are classified ashonju—more dangerous, stronger kaiju, andyoju—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 asdaikaiju.
Defense Force officers wearpowered 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 namedNumbers (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.
Following the destruction of their hometown by a kaiju, childhood friends Kafka Hibino and Mina Ashiro vow to join the Japanese Anti-Kaiju Defense Force. Mina ascends to become captain of the Third Division, renowned for her uniquely destructive marksmanship, while Kafka repeatedly fails the entrance exam and works on a cleanup crew disposing of kaiju remains. His resolve is renewed upon meeting Reno Ichikawa, a young coworker and fellow aspirant to the Defense Force. A parasitic creature subsequently enters Kafka's body, granting him the ability to transform into a humanoid kaiju. Designated "Kaiju No. 8", Kafka escapes military custody and enlists in the Defense Force, concealing his powerful alter ego.
Kafka and Reno pass the entrance examination and are assigned to the Third Division alongside Kikoru Shinomiya, a prodigious kaiju slayer. During their first mission, they confront another humanoid kaiju, "Kaiju No. 9", which Kafka fails to eliminate. He is later forced to reveal his kaiju form to save theTachikawa base from destruction during an attack by "Kaiju No. 10". Apprehended by Mina, Kafka is taken to Defense Force headquarters. He proves his value by defeating the Director General, Isao Shinomiya, in a duel. Kafka and Kikoru are then transferred to the First Division, led by Captain Gen Narumi.
No. 9 attacksShinagawa, and while two of its duplicates are destroyed, the genuine entity confronts and absorbs Isao Shinomiya, acquiring his Numbers 2 weapon, a powered suit of armor derived from Kaiju No. 2. Empowered, No. 9 escapes to prepare a full-scale invasion of Japan. In preparation, Kafka and Kikoru undergo intensive training; Kikoru inherits her mother's Numbers 4 weapon, while Reno acquires the Numbers 6 weapon and trains with the Fourth Division. During his own training with Vice-Captain Soshiro Hoshina at a shrine commemorating kaiju slayers of theMeireki era, Kafka perceives a spectral vision of an ancient warrior.
Months later, the invasion begins with kaiju designated Nos. 11 through 15 attacking specific Defense Force members. Gen, Soshiro, Kafka, and Kikoru defeat their assigned opponents, with Mina being the last to prevail. No. 9 uses the corpse of Kaiju No. 14 to teleport to Mina's location, intending to kill and absorb her to acquire her destructive power. Kafka reaches her in time with Reno's assistance. Together, Kafka and Mina defeat No. 9, but its corpse mortally wounds Kafka and is subsequently taken over by an ancient, powerful kaiju from the Meireki era that it had absorbed. This entity, Meireki, easily overpowers the remaining defenders.
The larval kaiju manifests in Kafka's mind and reveals it is a parasitic core born from the warriors Meireki slew, who were also responsible for theGreat Fire of Meireki (and thus the spirit he saw earlier). Saddened by the turn of events, it offers Kafka a choice: restoration of his human heart or transformation into a new core, permanently reviving him as Kaiju No. 8. Choosing to fight, Kafka revives as a Kaiju in a stronger form and, alongside Soshiro and Gen, confronts Meireki, who resurrects previous kaiju to battle them. Kafka, Kikoru, and Mina ultimately defeat Meireki, with Kafka delivering the final blow. After the battle, Kafka's health deteriorates, but he recovers from a four-month coma. His heart is restored by the spirit of Isao Shinomiya, who entrusts him with the future.
He returns to active duty at the Tachikawa base, welcomed by his comrades. A year later, Kikoru is promoted to vice-captain of the First Division, and Kafka is appointed platoon leader of the Third Division in recognition of his service. The Defense Force permits him to use his kaiju form when necessary, provided he exercises caution to remain undetected.
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.
—Shōnen Jump+ editor-in-chief Seijiro Nakaji on Naoya Matsumoto'stokusatsu influences.[3]
Naoya Matsumoto began his career in 2006 withNeko Romancer, published inJump Giga (then known asAkamaru Jump).[4] He authoredNekowappa!, which debuted inShueisha'sWeekly Shōnen Jump in 2009. The series continued aone-shot from theJG1 One-Shot festival.[5] He published another one-shot,Shikai Enbu, in the 2012 spring edition ofJump Giga (thenJump Next),[6] before starting his second serialization,Pochi Kuro, on Shueisha'sShōnen Jump+ website and application in 2014.[7]
Near the end of 2018, Matsumoto presented the initial story idea and outline forKaiju No. 8 toShōnen Jump+ deputyeditor-in-chief Seijiro Nakaji.[8] Influenced bytokusatsu media such as theUltraman series—particularlyUltraseven (1967)—as well asShin Godzilla (2016)[9] andPacific Rim (2013),[4] Matsumoto aimed to create a story about a protagonist who pursues a goal while concealing their identity from a hostile organization they have joined, which he considered an entertaining concept.[9] The premise of Kafka joining the Defense Force to fulfill his dreams was established early in development, though initial plans involved him maintaining a secret identity while living a normal life.[3] Kafka's predicament was partly inspired by Matsumoto's own career struggles in the manga industry.[10] Working onKaiju No. 8 was challenging for Matsumoto but allowed him to depart from his typical stories;[11] Nakaji noted the concept was unexpected, as Matsumoto had previously authoredfantasy series.[3]
Thepage layouts were designed for clarity, particularly onsmartphones, due to the manga's digital release.[3] Nakaji cited a fully coloredpanel in the second chapter as an example of utilizing the digital format in a way not feasible in a physical magazine.[8] A coworker suggested the kaiju codenames be based ontyphoon categorization to enhance their portrayal as disasters.[10] The kaiju designs drew frommythological creatures, animals, and plants. Kaiju No. 8's design was modeled afteroni, with its color scheme inspired by the filmTron (1982).[3]
Matsumoto worked with three assistants: Osamu Koiwai, responsible for background art; Jiro Sakura, who handled finishing work; and Mantohihi Binta, credited with weapon design.[12] For background art, Matsumoto provided astoryboard with panel compositions to Koiwai, who created a draft for approval before finalizing the art, a process taking three to four days. Koiwai shared his creative process for the series onYouTube.[13]
In August 2020,Kaiju No. 8 adopted a schedule of three weekly chapters followed by a one-week break.[14] From June 25, 2021, the series switched to a biweekly schedule.[15]
Production I.G producer Masashi Ohira broughtTetsuya Nishio onto the project as character designer and chief animation director, believing Nishio's designs facilitated animation and possessed a three-dimensional quality.[16] Nishio designed the human characters and humanoid kaiju.[16] In addition to serving as chief kaiju designer,Mahiro Maeda provided detailed imagery of kaiju anatomy for battle scenes. Ohira recruited Shinji Kimura as art director for his ability to create a realistic setting.[16]Toho Animation producer Katsuhiro Takei stated that Production I.G and studio Khara were selected due to similarities betweenKaiju No. 8 and their previous works. He noted the series' focus on daily life resembled Production I.G'sPatlabor (1989), while its setting evoked Khara'sNeon Genesis Evangelion (1995). Involving both studios aimed to recreate the aesthetic of 1990s anime.[17]
The anime combinedhand-drawn and3D animation.[18][19] Lead 3D animation director Masaru Matsumoto worked with a small team usingAutodesk 3ds Max andBlender; production began in March 2022 and continued during the broadcast.[18] Directors Tomomi Kamiya and Shigeyuki Miya identified sequences requiring 3D animation during storyboarding,[19] while Kimura and mechanical designer Shinobu Tsuneki collaborated with the team to evoke theaesthetics of Production I.G films likePatlabor andGhost in the Shell (1995), emphasizing realistic military combat.[18] Extensive 3D animation was used for battles against numerous monsters and for dynamic camera work in action sequences.[19] StudioKhara, in collaboration with the creative agency WOW, produced theopening sequence. Directed byHibiki Yoshizaki with Kouhei Nakama as CG director, the sequence aimed to depict the origin of thekaiju.[20]
Written and illustrated byNaoya Matsumoto,Kaiju No. 8 started onShueisha'sShōnen Jump+ app and website on July 3, 2020.[21] The series ended with the release of its 129th chapter on July 18, 2025.[22][23] Shueisha has collected its chapters into individualtankōbon volumes. The first volume was released on December 4, 2020;[24] a promotional video for the volume, presented as anews program, was shown on the big screen of Yunika Vision atSeibu-Shinjuku Station from December 4–10, 2020.[25] The 16th and final volume was released on September 4, 2025.[26]
Viz Media began publishing the series in English on its website on August 2, 2020, under the titleKaiju No. 8,[27] and on February 19, 2021, it announced that it had licensed the series for print in English,[28] releasing the first volume on December 7, 2021.[29] Shueisha began publishing chapters of the series on itsManga Plus website and app on July 22, 2020, under the titleMonster #8 in English and several other languages.[30][b] On March 30, 2023,Manga Plus announced that it would includeKaiju No. 8 in the title of the version of the manga on its service.[31]
Aspin-off manga illustrated by Kentaro Hidano, titledKaiju No. 8: B-Side (怪獣8号 side B) ran from January 5 to July 12, 2024, onShōnen Jump+.[39] The spin-off is based on thelight novelKaiju No. 8: Exclusive on the Third Division, written by Keiji Andō, and features side-stories of Defense Force members.[40][41] Shueisha collected its chapters in twotankōbon volumes, released on April 4 and October 4, 2024.[42][43] Shueisha and Viz Media began publishing the series in English on January 4, 2024, Shueisha on itsManga Plus website and app and Viz Media on itsShonen Jump website and app.[44] Viz Media released the volumes in print on April 8 and September 2, 2025.[45][46][47]
Another spin-off manga, illustrated byKizuku Watanabe [ja], titledKaiju No. 8 Relax, began its serialization inSaikyō Jump on June 4, 2024, and onShōnen Jump+ on June 7 of the same year.[48] Viz Media began publishing the series in print, with the first volume released on December 2, 2025.[49][50]
A 4-chapter side-storylight novel titledKaiju 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.[51][52] On February 2, 2024, Viz Media announced that it had licensed the light novel for print in English.[53] It was published on December 3, 2024.[54]
Crunchyroll streamed the series as it aired in Japan, as well as dubbed versions an hour after its television premiere,[64][65] which includes English, Brazilian Portuguese, French, German, Italian, Spanish, Latin American Spanish, Hindi, Telugu, and Tamil.[66][67] The first season was released inBlu-ray on December 9, 2025.[68]Medialink licensed the series for streaming in Southeast Asia on its Ani-One AsiaYouTube channel.[69]
After the airing of the final episode, a sequel was announced.[70] It was announced that it would be a second season, which aired from July 19 to September 27, 2025.[71][72][73][74] 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;[75] the "Hoshina's Day Off" episode aired on TV Tokyo and affiliates on July 5 of the same year.[74] It was announced that the film would have a worldwide release,[76] later revealed to be screenings in North America,[77] the United Kingdom, and Ireland with distribution bySony Pictures Entertainment and under the titleKaiju No. 8: Mission Recon.[78] The film was also released in India.[79] Crunchyroll is also streaming the second season.[70]
In December 2025, a "conclusion arc" to the anime series alongside an anime short titled "Narumi's Weekday" (鳴海の平日,Narumi no Heijitsu) were announced.[80]
A series of short episodes, titledMinute! Kaiju No. 8 (ミニっと！かいじゅう8号,Minitto! Kaijū 8-gō), started onToho Animation's YouTube channel on December 6, 2024.[81][82]
The music was composed byYuta Bandoh creating afilm 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 ofThe Internet and Suni MF are also featured on the soundtrack which was released on June 26, 2024.[83] The opening theme song for the first season is "Abyss", performed byYungblud, while the ending theme song is "Nobody", performed byOneRepublic.[84][62] The ending theme song for the "Hoshina's Day Off" original episode is "Invincible", performed by OneRepublic.[76] The opening theme song for the second season is "You Can't Run From Yourself", performed byAurora,[85] while the ending theme song is "Beautiful Colors", performed by OneRepublic.[86]
Kafka Hibino is featured as a playable character in the video gameCaptain Velvet Meteor: The Jump+ Dimensions that was released on theNintendo Switch on July 28, 2022.[87]
A life-size statue of Kafka's kaiju form was displayed at theTachikawa Station on theChūō Main Line from April 26–29, 2024. Kafka's voice actorMasaya Fukunishi was appointed as the ceremonial one-day manager at theKaiju No. 8 store in the station. The statue was displayed in four other places from May 1 to June 16, 2024.[88]
A video game project, titledKaiju No. 8 the Game, was announced in June 2024. Developed by Akatsuki Games, it was released for smartphones on August 31, 2025,[89][90] and forWindows (viaSteam) on October 1.[91]
According to Yūta Momiyama, the deputy editor-in-chief ofShōnen Jump+,Kaiju No. 8, along withSpy × Family, have been very popular and are doing especially well on theManga Plus service.[92] In December 2020, it was reported thatKaiju No. 8 surpassed 30 million views, making it the fastestShōnen Jump+ series to achieve this feat, and each new chapter published surpasses one million views.[93] In February 2021, the series reached 70 million views.[94] In April 2021, the series reached over 100 million views.[95] In February 2023, the series reached 400 million views.[96] The series ranked tenth onAnimeJapan's 5th "Most Wanted Anime Adaptation" poll in 2022.[97]
TheSchool Library Journal listed the first volume ofKaiju No. 8 as one of the top 10 manga of 2021.[98] It ranked third onTakarajimasha'sKono Manga ga Sugoi! 2022 list of best manga for male readers.[99][100][101] The series ranked second on the Nationwide Bookstore Employees' Recommended Comics of 2022.[102] The series was included inPolygon's list of the best comics of 2021,[103]Kotaku's list of the 11 best manga series of 2021[104] andThe Fandom Post's list of the 12 best manga series of 2020.[105]
The series' first volume sold 90,831 copies in its first week,[106] and 69,404 copies in its second week.[107] By December 2020, the first volumes had over 430,000 copies in circulation (print and digital).[108] 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.[109] By March 2021, the manga had over 1 million copies printed physically and 200,000 copies sold digitally, making it the fastestShōnen Jump+ series to reach 1 million copies in circulation,[110][94] and 20 days later reached 1.5 million copies in circulation.[111] By June 2021, the manga had 2.5 million copies in circulation,[112] and by middle of the month it reached 3 million copies.[113][114] By September 2021, the manga had over 4 million copies in circulation;[115] over 5.5 million copies in circulation by December 2021;[116] over 6.7 million copies in circulation by March 2022;[117] over 7.8 million copies in circulation by July 2022;[118] over 8 million copies in circulation by August 2022;[55] over 10 million copies in circulation by December 2022;[119] over 11 million copies in circulation by March 2023;[120] over 13 million copies in circulation by April 2024;[121] over 14 million copies in circulation by June 2024;[122] over 15 million copies in circulation by July 2024;[123] over 16 million copies in circulation by September 2024;[124] over 18 million copies in circulation by March 2025;[125] and over 19 million copies in circulation by September 2025.[126]
The series' fifth and sixth volumes were among the 30 best-selling manga volumes of 2022.[127] The ninth volume was among the best-selling manga volumes of 2023.[128] Volume 10 wasShueisha's seventh highest first print run manga volume of 2023–2024 (period from April 2023 to March 2024), with 600,000 copies printed;[129] volume 12 had an initial print run of 500,000 copies printed, making it the publisher's eighth highest first print run manga volume of 2024–2025 (period from April 2024 to March 2025).[130]
In the United States, individual volumes have ranked onCircana (formerly NPD)Bookscan's monthly list since 2021[131] and onThe New York Times' Graphic Books and Manga bestseller monthly list since 2022.[132] The series' first volume sold sold 118,000 copies in 2022,[133] and the fifth one sold 52,000 copies in 2023.[134]
In France, the series sold 22,041 copies in its first week, making it the best-selling debut of manga in France.[135] By April 2023, the series sold 888,888 copies in France.[136] In Italy, the first volume had a first print run of 245,000 copies (including various editions), surpassingDemon Slayer: Kimetsu no Yaiba, which has 200,000 copies in circulation per volume.[137]
The series' first volume has been positively received.[c] The series has been praised for its premise,[138] which has drawn comparisons to theUltraman series,[146] for its art,[d] particularly the kaiju designs[e] and for its comedy.[138][139][143] Kafka Hibino has been singled out as an endearing character[147] and a novel aspect of the series due to his age.[f] However, the first volume received some criticism for itsformulaic beginning[138][148] as well as, what was deemed as, inconsistent art quality and fastpacing that sacrifices character development.[149]
The series premiere was positively received. In a series of positive reviews forAnime 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."[162] James Beckett complementedProduction 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."[162] Nicholas Dupree praised the show's action sequences andworldbuilding, 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.[162]Digital Spy's Janet A Leigh praised the series' premiere for its animation and action, comparing its premise toAttack on Titan but with a more light-hearted tone.[163] Toussaint Egan ofPolygon similarly described the series' premise as a combination ofMy Hero Academia andPacific Rim while praising its tone, dramatic moments, action and art direction.[164]
Grant Jones ofAnime News Network wrote positively about the first season[165] with high praise for the season's second half.[g] Episode 6 ("Sagamihara Neutralization Operation at Daybreak") provided story elements that expanded upon the world of the series.[166] 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.[167] 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.[168] The final two episodes were praised for their overall presentation in terms of animation, direction and storyboarding[169][170] with the eleventh episode ("Kaiju No. 8 Captured") bringing the "visual fidelity to the highest levels in the season thus far"[169] while the final episode ("Kafka Hibino") provided an effectivecliffhanger for the second season.[170] Criticisms of the season were aimed at the character designs which were described as "rather bland" and "very flat."[171] Episode 3 ("Revenge Match") was seen as a low point of the season due to its reliance ontropes and its "lackluster" animation.[172] Isaiah Colbert ofIGN wrote positively of the first season saying that even though the series follows standard tropes of "othershōnen anime," its balance of action and drama allowed for "character-rich moments" that added depth and intrigue to the story.[173]
^Polo, Susana; Maveal, Chloe; Schenkel, Katie; Babu, Ritesh (December 7, 2021)."The best comics of 2021".Polygon.Archived from the original on March 7, 2023. RetrievedMarch 13, 2023.
^Dacey, Katherine; Gaffney, Sean; Smith, Michelle (April 21, 2022)."Bookshelf Briefs 4/21/22".Manga Bookshelf.Archived from the original on April 21, 2022. RetrievedApril 22, 2023.
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