Kaiju No. 8 (Japanese: 怪獣8号, Hepburn: Kaijū 8-gou), also known in English as Monster #8, is a Japanese manga series written and illustrated by Naoya Matsumoto. It has been serialized for free on Shueisha‘s Shōnen Jump+ application and website since July 2020, with its chapters collected in ten tankōbon volumes as of August 2023. The story follows Kafka Hibino, a man who, after ingesting a kaiju, gains the ability to turn into one 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.

Viz Media has licensed the series for English release in North America. An anime television series adaptation produced by Production I.G is set to premiere in April 2024. By March 2023, the manga had over 11 million copies in circulation. The series has been praised for its premise, characters and art.

Synopsis

Setting

Kaiju No. 8 is set in a world in which monsters named kaiju regularly cause disasters. Japan is the country with the highest rate of kaiju attacks in the world and, to combat them, it establishes the Anti-Kaiju Defense Force (日本防衛隊, Nihon bōei-tai, lit. “Japanese Defense Force”). 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 the 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 power 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 vary from person to person depending on their ability with a maximum of 100%. The Defense Force consists of general officers and platoon leaders, with varying levels of unleashed combat power, and captains and vice-captains whose combat power exceeds 90% and who lead divisions. Daikaiju remains are used to create stronger weapons named Numbers (ナンバーズ, Nanbāzu) that some individuals can use if they are deemed compatible and that are named after the daikaiju they are made from.

Plot

After their town is destroyed by kaiju, childhood friends Kafka Hibino and Mina Ashiro both vow to become members of the Defense Force to fight kaiju together. Mina, now 27, has since become the captain of the Defense Force’s Third Division while Kafka, now 32, has failed the examination numerous times and works as a member of a clean-up crew that dispose of kaiju remains after battle. Kafka meets a young part-time worker in his company, Reno Ichikawa, an aspiring Defense Force member, who reignites his desire to become part of the Defense Force. However, a small kaiju enters Kafka’s body through his mouth and he gains the ability to turn into a kaiju. After escaping from the Defense Force, Kafka is given the code name “Kaiju No. 8” and decides to apply while keeping his form a secret.

Kafka and Reno are able to pass the examination and are inducted into the Third Division together with Kikoru Shinomiya, a kaiju-slaying prodigy, who finds out about Kafka’s condition after he saves her from a humanoid kaiju, later named “Kaiju No. 9,” who becomes their primary adversary. While fighting off an attack orchestrated by No. 9, Kafka reveals his kaiju form when he transforms to save the Third Division base from being destroyed and is, reluctantly, apprehended by Mina and taken into custody to be disposed of. While imprisoned, Kafka is tested in battle by the Director General of the Defense Force, Isao Shinomiya, who uses the Numbers 2 weapon made from the remains of Kaiju No. 2. Kafka survives the battle proving that he can control himself while transformed and avoids being disposed of. Kafka is transferred, along with Kikoru, to the First Division led by captain Gen Narumi where they are tasked to prevent another attack planned by No. 9. Kafka, Kikoru and Gen succeed in defeating two versions of No. 9 which are revealed to be decoys. The real one attacks Isao and absorbs him and his Numbers 2 weapon after which No. 9 becomes stronger and prepares for an invasion of Japan with new kaiju.

Characters

Kafka Hibino (日比野カフカ, Hibino Kafka) / Kaiju No. 8 (怪獣8号, Kaijū 8-gō)

Voiced by: Masaya Fukunishi

A 32-year old man with dreams of joining the Defense Force to fight alongside his childhood friend Mina Ashiro. He gives up on his dream after failed, past attempts to join the Defense Force and starts working in a kaiju disposal company as a cleaner. He gains the ability to turn into a kaiju after a small one enters his body through his mouth. After escaping from the Defense Force he is subsequently dubbed “Kaiju No. 8”. In his kaiju form he has a fortitude level of 9.8, making him the strongest kaiju identified by the Defense Force, as well as superhuman strength, speed, regeneration and the ability to detect other kaiju. Due to his low unleashed combat power in his human form he utilizes his knowledge of kaiju anatomy, from his work in the disposal industry, to help his squad mates defeat kaiju.

Reno Ichikawa (市川レノ, Ichikawa Reno)

Voiced by: Wataru Kato

An 18-year old man who starts working in the same company as Kafka with plans to join the Defense Force. He becomes friends with Kafka and helps him hide the secret of his kaiju form. Reno is a considered to be a promising recruit and quickly becomes one of the Defense Force’s strongest assets. He is compatible with the Numbers 6 weapon made from the remains of Kaiju No. 6 that has a fortitude level of 9.6 and that devastated the Defense Force prior to the events of the series. The Numbers 6 weapon takes the form of a suit of armor that increases Reno’s strength and speed and gives him the ability of cryokinesis.

Mina Ashiro (亜白ミナ, Ashiro Mina)

Voiced by: Asami Seto

The 27-year old captain of the Third Division of the Defense Force. She is Kafka’s childhood friend with whom he vowed to fight against kaiju. She is one of the strongest officers in the Defense Force, her personal weapon is a handheld cannon making her effective against giant-sized kaiju.

Kikoru Shinomiya (四ノ宮キコル, Shinomiya Kikoru)

A 16-year old girl who joins the Third division together with Kafka and Reno. A kaiju-slaying prodigy, Kikoru is one of the greatest talents in the Defense Force and has the highest recorded unleashed combat power as a recruit. Her father, Isao, is the Director General of the Defense force while her mother, Hikari, was a captain who died in the line of the duty while fighting off a kaiju invasion led by Kaiju No. 6 prior to the events of the series. She uses a giant axe as her personal weapon and inherits her mother’s Numbers 4 suit which gives her the ability of flight.

Soshiro Hoshina (保科宗四郎, Hoshina Soshiro)

The vice-captain of the Third Division. He is a skilled swordsman who is particularly good at fighting smaller kaiju. Prior to becoming vice-captain he was advised by his superiors to quit becoming a field officer due to his ineffectiveness with ballistic weaponry. Mina was one of the only ones who valued his skill as a swordsman and asks him to become her vice-captain. After defeating Kaiju No. 10, Soshiro gains the sentient Numbers 10 weapon that takes the form of a suit of armor with a tail that can be used for attacks.

Isao Shinomiya (四ノ宮 功, Shinomiya Isao)

The Director General of the Defense Force and Kikoru’s father who is considered to be one of the strongest combatants in the history of the Defense Force. Isao uses the Numbers 2 weapon made from the remains of Kaiju No. 2 in the form of a powered suit of armor and gauntlets, which gives him superhuman strength and the ability to use sonic blasts. Isao starts teaching Kikoru how to fight against kaiju after the death of his wife, Hikari.

Gen Narumi (鳴海 弦, Narumi Gen)

The captain of the First Division of the Defense Force. He is considered to be the strongest active captain in the Defense Force. Gen uses the Numbers 1 weapon made from the remains of Kaiju No. 1. The weapon takes the form of a powered suit of armor and a pair of retinal implants that give Gen the ability to predict enemy movements allowing him to always land his attacks. His personal weapon is a rifle with a bayonet.

Kaiju No. 9 (怪獣９号, Kaijū 9-gō)

A sentient, humanoid kaiju who can create other kaiju as well as absorb humans, taking their appearance and memories. No. 9 infiltrates society by disguising himself as a human and orchestrates most of the catastrophes that befall the Defense Force. It absorbs Isao Shinomiya and his Numbers 2 weapon which greatly increases its strength and ability to create stronger kaiju.

Kaiju No. 10 (怪獣10号, Kaijū 10-gō)

A sentient, humanoid kaiju that leads an attack on the Third Division’s base. It is ultimately defeated and apprehended by Soshiro Hoshina and Mina Ashiro. While imprisoned, No. 10 reveals that it was created by No. 9 and asks to be turned into a Numbers weapon to be used by Soshiro Hoshina. It is the first kaiju to be made into a Numbers weapon while still alive and retains its sentience. No. 10 has a maximum fortitude level of 9.0.

Manga

Kaiju No. 8 is written and illustrated by Naoya Matsumoto. The series began 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. On 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, 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 August 4, 2023, ten 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, in English and several other languages, on its Manga Plus website and application on July 22, 2020 under the title Monster #8. 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. Publisher Star Comics organized a similar promotion for the release of the first volume in Italy by displaying a mural in the Porta Genova metro station in Milan.

Volume list

Chapters not yet in tankōbon format

These chapters have yet to be published in a tankōbon volume. They were serialized on Shōnen Jump+.

• Chapter: 82–94

Light novel

A 4-chapter side story light novel, written by Keiji Ando and illustrated by the original manga author, Naoya Matsumoto, was released on November 4, 2022.

Anime

On August 4, 2022, it was announced that the manga would be receiving an anime adaptation. It was later revealed to be a television series set to premiere in April 2024, with Production I.G animating and Studio Khara supervising the kaiju designs and artworks.

Other media

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.

Reception

Popularity

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.

Manga

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.

Sales

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; and over 11 million copies in circulation by March 2023.

Individual volumes have ranked on NPD Bookscan‘s monthly list since 2021 and on the The New York Times‘ Graphic Books and Manga bestseller monthly list since 2022. The series’ first volume sold 118,000 copies in the United States in 2022.

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.

Critical reception

The series’ first volume has been positively received by various publications with particular praise aimed at its artwork which has been described as “gorgeous and incredibly detailed.” Matsumoto has received praise for his use of page spreads for storytelling purposes and for his kaiju designs. Kafka Hibino has also been singled out as an endearing character and a novel aspect of the series due to his age. The series has also been lauded for its comedy.

The first volume has drawn a mixed reception with some publications. Dallas Marshall of Comic Book Resources thought that “the artwork of Kaiju No. 8 flip-flops between passable and outstanding” but believed that the series could become better with subsequent volume releases. Katherine Dacey of Manga Bookshelf was more critical of the series describing the first volume as formulaic and writing that “Matsumoto is more interested in writing a monster-fighting manga than writing a thoughtful story about a man who unwittingly becomes a monster.”

Awards and nominations

Notes

Kaiju No. 8
First tankōbon volume cover, featuring Kafka Hibino in his monster form
怪獣8号 (Kaijū 8-gou)
Genre	Adventure Science fantasy
Manga
Written by	Naoya Matsumoto
Published by	Shueisha
English publisher	NA: Viz Media
Imprint	Jump Comics+
Magazine	Shōnen Jump+
Demographic	Shōnen
Original run	July 3, 2020 – present
Volumes	10 (List of volumes)
Light novel
Kaijū 8-gō Mitchaku! Dai-3-butai
Written by	Keiji Ando
Illustrated by	Naoya Matsumoto
Published by	Shueisha
Imprint	Jump J-Books
Demographic	Male
Published	November 4, 2022
Anime television series
Studio	Production I.G
Original run	April 2024 – scheduled
Anime and manga portal