Kei Kurono

Hiroya Oku developed Kurono's character with the goal of having manga readers identify with him. He was also created to "make a synthesis of the basic conditions for a work of entertainment".[1] Oku originally created Kurono as a character who would fit in a college comedy series. To make him the Gantz character readers would identify with, the author gave him traits such as his sense of insecurity, fears and other complexes.[2] Before the manga started serialization, Oku told his assistants that with Kurono's exception, all the major characters from the series would die in order to surprise readers with plot twists.[3] As the series continued, Oku felt that Kurono was his favorite character though he stated it might have been because he was the main character. In the making of the live-action adaptations, he felt that Kazunari Ninomiya fit the image of Kurono well.[4] In another interview, Oku said Masaru Kato was his favorite character based on his heroic traits in contrast to Kurono who he felt was a more flawed character with conflicting thoughts.[5]

Gantz: O director Yasushi Kawamura said that as a result of Kato replacing Kurono as the protagonist of the film, he felt unsure of the audience's reaction even if they had not read the original manga.[6] For the live-action series, director Shinsuke Sato said that Ninomiya was perfectly cast for the role, that he visually resembled the manga character and represented the current audience. According to Sato, Kurono goes through some "very subtle changes of the heart" in the manga and Ninomiya could portray those particular qualities.[7]

While Daisuke Namikawa and Chris Ayres voiced Kurono in the anime, Yūki Kaji and Lucien Dodge voiced him in the CGI film.

Kurono's Japanese voice actors were Daisuke Namikawa in the anime and Yūki Kaji in Gantz: O. Namikawa stated that his first impression of Kurono was that of an attractive person. However, once reading his lines while interacting with other characters, Namikawa found Kurono cynical and later stated that Kurono was bold due to how he often spoke his mind. Because such people are rare, he felt that viewers would sympathize with Kurono. Due to the frequency of recurring characters dying in the anime, Namikawa joked to fellow actors if they would stop working together and feared Kurono might also die in the plot. He admitted wishing that Kurono would obtain a power to get through difficult situations, and enjoyed seeing Kurono surviving the action scenes in each story arc. Once doing so, Namikawa felt the character became a hero as well as a "great person". Despite liking his character, Namikawa felt it was challenging to voice Kurono.[8]

Kurono's English voice actors were Christopher Ayres in the anime series and Lucien Dodge in Gantz: O. Ayres had previously worked with Matt Greenfield of ADV Films dubbing for Megazone 23. Ayres auditioned for Kurono and for Kato, and was given the former role the following day. He originally thought he was going to voice Kato, but the director felt he was more fitting for voicing Kurono, whom Ayres felt was a "jerk". Initially, most of Ayres's friends told him Kurono was a "jerk and an ass" which left a sudden impression on him. Greenfield did not want Ayres to know of his character online, instead wishing to learn of Kurono while working on the English dub. Upon working in the Gantz dub, he stated "I've always been drawn to anti-heroes and characters with an edge, and Kei is definitely both. I love the fact that he's flawed and makes mistakes [...] Perfect people are so much more boring to play as an actor." He enjoyed working as the character to the point of relating with him.[9]

Multiple reactions to Kurono were given by critics for anime, manga and other media. James Musgrove of IGN found his anime rendition to have "all-too-human motivations" juxtaposed with an emergence of his "hidden good side" as the story progresses, and implied that he was an unconventional protagonist. He praised Chris Ayres's acting on Kurono, finding him one of the anime's best voice actors despite it being one of his early works.[19] In the live-action review, Otaku USA called the character an "uneven protagonist" similar to how Kurono is portrayed in the manga and praised his connections with Kato and Kishimoto. Despite criticizing his role, the site compared him with comic book character Peter Parker as both had yet to develop themselves.[20] DVDTalk stated that while the character initially was introduced like a "jerk", he becomes more likable in the anime series as it progressed and liked his interactions with Kishimoto.[21] Anime News Network found Kurono a more-attractive character stating that he "may be one of the freshest and most interesting anime protagonists of the past few years" and that he becomes more interesting across the action scenes, making his relationship with Masaru Kato better received. The anime's exclusive last story arc was noted to make Kurono a more-appealing individual.[22] Fandom Post noted the contrast between the pacifist Kato and the berserker Kurono as the latter does not care about killing enemy aliens and ends up going through an entertaining growth during the final arc where he rejects being forced to fight human beings.[23] Mania Entertainment stated that Kurono has "halfway decent hero material wrapped up in a slimeball package" for how he manages to fight his enemies based on his own childhood when he was used to face multiple challenges. However, Mania still stated that his portrayal of sexual desires might scare young viewers.[24]

The character also received a large number of negative comments. AnimeFringe described Kurono as "the token angst-filled high school student" and criticized his focus on puberty, finding Masaru Kato much more likable due to their differences.[25] In a following review, the site also criticized Kurono's concerns shown in the anime series to the point that the reviewers might lose interest in the series.[26] THEM Anime Reviews similarly found Kurono to be an unlikable character, described him as a "soulless monster" and went on to say "he's mean, extremely selfish, very cynical, and you almost get the feeling he's happy that way, or at least unapologetic. There is no fall from grace; he's already fallen, and has no desire to get back out." A noted example was his inaction when Kei Kishimoto is nearly violated by a gangster in contrast with Kato who tries to save her.[27] Another review from the site noted that despite Kurono's character arc across the series, his changes are brief and Kato was more likable.[28] Anime News Network felt that while Kurono underwent multiple personality changes across the manga, the site stated Oku lacked the talent to make it appealing and heavily criticized his overshadowing relationships with secondary characters.[29]

Critics have also commented on Kurono's role across the live-action films. While noting that Kurono goes through a notable arc in the live-actions, Hobby Consolas found Ninomiya's acting too forced and at the same time his appearance was noted to lack Kurono's physical traits.[30] UK Anime Network praised Kazunari Ninomiya's acting in the second live-action film which manages to make the character more appealing.[31] While finding Kurono more likable than his manga persona based on his growth across the first film and his romantic relationship, Anime News Network stated that fans might miss his original character traits.[32] However, for the second film, another writer for the site said he enjoyed Kurono's growth alongside his relationship with Tae.[33] Japanator agreed with his comments regarding Ninomiya's role due to the notable growth he makes while also finding the actor attractive.[34] Twitch Film stated that Ninomiya is a "standout" for the way he portrays Kurono's character development across the first film.[35] The Japan Times found the relationship between Kurono and Tae simple, referring to them as "a hero (Kei) saving his princess (Tae) from the dragon (the black-clads)."[36]