Seiyuu Digest #60 – Kentaro Kumagai

Kentaro Kumagai is one of the many young seiyuu picking up on the fast pace of the seiyuu industry, working hard to stay afloat among the competition.

Kentaro Kumagai

KANJI: 熊谷 健太郎

BORN: February 16, 1994

OCCUPATION: seiyuu, radio personality, singer

HEIGHT: 174 cm

A note, this article received a soft update in January 2021.

Some information below may be dated or not updated.




In the seiyuu industry, few are those who manage to have roles in their debut year and even if that is the case, there aren’t many who’ll get so lucky so as to keep on a regular stream of roles.

With that said, Kumagai‘s career has been a mirror of this particular situation. Having debuted in 2012, his debut role was as two different minor characters in the supernatural and comedy anime Haitai Nanafa.

From those roles onward, Kumagai went under the radar in the seiyuu industry, only to make a comeback a couple of years later.

2015 –

It took us 3 years to hear Kumagai‘s name in the seiyuu industry.

Naturally, after being away for so long in this industry it was more than expected that his first roles since his time away would be minor roles or supporting characters.

Aston Altland in Gundam Iron-Blooded Orphans

In 2015, Kumagai was cast as Aston Altland in both seasons of Gundam Iron-Blooded Orphans. Altland is just as his looks, cold and reserved as his past delves into years of slavery he had to endure.

As one of the orphans in the plot, this man, later on, becomes less closed to human interaction and eventually makes friends with other characters.

As Kumagai‘s first role after a couple of years of the industry, he had one thing to his advantage.

Gundam Iron-Blooded Orphans was an anime with quite a lot of attention at it is one of the many installments of the franchise. That being the case, he had the chance to do his best as Altland and catch the eye of people, something that he desperately needed since he was being practically treated as a rookie in the industry.

Although from 2015 onward Kumagai started to be noticeably more prolific, when you analyze his repertoire you’ll understand that the wide majority of entries are of minor characters in popular anime.

Those did get him some exposure to the industry but are not enough to get him to be noticed by primarily the producers and lastly the fans for his talent and skills as a seiyuu.

Haruhiko Takase in Tsurezure Children

So then, in 2017, Kumagai got cast as Haruhiko Takase in Tsurezure Children the comedy anime.

As Takase, Kumagai played a shy boy that has a crush on one of his classmates, but due to his personality, the misunderstandings between the two are more than just a few.

Even though the anime got mixed reviews, as some praised it for being able to be captivating and others criticized it for being too exaggerated at times, one thing is certain, Kumagai needed the exposure and that was what he got, even if his character is supporting.

2017 was also the year Tsuki ga Kirei aired, and as if Kumagai‘s momentum could not stop growing, he got cast as Tsubasa Kaneko, a supporting role; and in The iDOLM@STER SideM as he reprised his role as Hideo Akuno.

If there is one year that showed a turn in the tide for Kumagai is 2018. Getting cast as the main character in an anime is perhaps the ultimate dream of any rookie seiyuu in the industry, and he managed to accomplish it rather soon.

Theo Cornaro in Grancrest Senki

In 2018, Kumagai got cast as the protagonist, Theo Cornaro, in the anime Grancrest Senki. Granted that getting the main role won’t be the exact recipe for success, in fact, getting the role is but the starting line, afterwards it is up to the seiyuu to turn that opportunity into something more or not.

Kumagai‘s case was the latter.

Theo Cornaro is the protagonist that has achieved his dream through sheer will and that in itself already shows how righteous he is, as it also demonstrates how Cornaro has the power to make his dreams come true.

Additionally, he also has quite the noble ideals that make him pursue certain paths so as to once again turn his dreams into reality.

For a seiyuu as Kumagai, that had some difficulties to overcome in the years following his debut, a role such as Cornaro is the perfect opportunity to make one’s name popular or at least for fans to notice the seiyuu.

Yuuma Gojou in Hinomaruzumou

As if the year had not been smiling enough over Kumagai, the seiyuu also got one of the main roles in the sports anime Hinomaruzumou as Yuuma Gojou.

A third-year in high school and a member of the sumo club, Gojou has a powerful aura around him and impresses with a strong built.

Aside from his physical appearance, Gojou starts off being arrogant and tough as he is considered to be the strongest in his school, Daichi High.

For the rest of 2018, Kumagai reprised his role in Idolm@ster Side M mini and also reprised his role in Free!: Take Your Marks as Aoba Usami. He got cast in the OVAs of Yarichin☆Bitch-bu as Tooru Fujisaki. In 2019, he counts with an appearance in Card Fight !! Vanguard.

Other roles in Kumagai‘s repertoire include names such as:

  • Starmyu (2015),
  • Orange (2016),
  • Gate: Jieitai Kanochi nite, Kaku Tatakaeri 2nd Season (2016),
  • Super Lovers (2016),
  • Tanaka-kun wa Itsumo Kedaruge (2016),
  • Marginal#4: Kiss kara Tsukuru Big Bang (2017),
  • Shingeki no Bahamut: Virgin Soul (2017),
  • Code:Realize – Sousei no Himegimi (2017),
  • IDOLiSH7 (2018),
  • Hataraku Saibou (2018) and
  • SSSS.GRIDMAN (2018).


When it comes to Kumagai‘s working in the radio branch of the entertainment business, one must say that he has just begun taking his first steps.

It is true that Kumagai has the talent to host a radio show as he adds in just the right amount of seriousness and comic relief when he hosts a show.

His first entry in his repertoire was as the host of Idol Master Side M Radio 315 pro Night! (2016), and although it was only for a limited amount of time, it made Kumagai more comfortable with the whole radio hosting idea.

Then came Kumagami Coffee Store-Premium Blend- (2017-), a radio show that Kumagai has been hosting alongside fellow seiyuu Sho Nogami.

Kentaro Kumagai・Tetsuei Sumiya no Koibana te nanda tanda!?

Still in 2017, Kumagai was hosting another radio show, MAN TWO MONTH RADIO of Kentaro Kumagai, however, taking into account the radio show’s 1-month format, that same show ended in 2018.

And currently, he has been hosting his own radio show, Kumagai Kentaro’s Horisage! as well as in Kentaro Kumagai・Tetsuei Sumiya no Koibana te nanda tanda!?. 

Stage Acting / Live Acting

Although not that active in this field, the truth is that Kentaro Kumagai does have experience with stage and live acting.

In 2013 Kumagai did some work with the theater troupe called Poseidon for Rent.

K4 Company (2021)

K4 Company THE MOVIE

In 2021, Karino joined the supporting cast alongside fellow male seiyuu Tsubasa Yonaga, Gakuto Kajiwara, Jun Kasama, Sho Karino, Yuuki Shin, and Yuya Hozumi in the movie K4 Company THE MOVIE.

And in 2021, he made his debut as an actor in the live-action movie: K4 Company.

Drama CDs

It is not mandatory for seiyuu to be prolific in the drama CDs department, and in fact, Kumagai is not the type of seiyuu whose focus appears to be in this branch of the department industry.

Still, he has some entries in his repertoire, most of which Kumagai is reprising his roles in the respective anime as is the case in the Idolm@ster SideM drama CDs or Mobile Suit Gundam‘s.

Aside from that, he has also other entries, in the BL industry, which include names such as Caste Heaven, Yarichin ⭐︎ Bitch-bu, No Color Baby, and Sayonara Alpha.


Much like his roles in anime, Kumagai branched to voice characters in-game around 2015 with a role in Idolm@ster SideM as FRAME‘s Hideo Akuno.

The character is featured in THE IDOLM@STER SideM and SideM LIVE ON ST@GE!, the two-game iterations stemming from the SideM franchise.

Following this role, he got cast in the extremely popular game A3! as Omi Fushimi, one of the members of the Autumn troupe.

Omi Fushimi in A3!

Fushimi is the member that does the majority of the cooking and cleaning chores and appears to always be ready to help others, so in other words, he is considered to be a “mother” for Autumn troupe’s members, as well as the resident cook for the dorm.

Initially hired to be the photographer for the Summer troupe’s debut play, Fushimi then becomes a full-fledged member of the Autumn troupe.

When 2018 came, Kumagai reprised his role as Theo Cornaro in the Grandcrest Senki games, and in the same year, he also has a couple more roles, such as in Idol Fantasy as Soma Kanon, one of the members of Brave Hearts, one of the game’s units.

In 2019, Kumagai has been cast in Blue Exorcist as Alex Summons and in Op8 ♪ as Itsuki Reizei.


FRAME (2014 -)


This unit consists of Hideo Akuno (Kentaro Kumagai), Ryu Kimura (Kento Hama), and Seiji Shingen (Takuya Masumoto), all of the members being former civil workers.

Up until now, the trio has released one single, THE IDOLM@STER SideM ST@RTING LINE-08 FRAME (2015). Aside from these singles, FRAME has participated in several cross-unit and solo song projects within the franchise.

The trio has participated so far in three IDOLMASTER SideM stages: 1st STAGE 〜ST@RTING!〜 (2016), 2nd STAGE 〜ORIGIN@L STARS〜 (2017) and 3rd STAGE 〜GLORIOUS ST@GE!〜 (2018).

They also participated in the fan meeting tour “GREETING TOUR 2017 ~BEYOND THE DREAM~” in 2017 and  THE IDOLM@STER SideM’s Five-St@r Party!! in 2018.

Autumn Troupe (2017 -)

Autumn Troupe

As mentioned above, Kumagai is a member of the Autumn Troupe. He voices Omi Fushimi, Autumn Troupe’s talented actor, usually the bad guy/villain in their plays (picture above, the third from left to right).

The troupe initially counted with Chiharu Sawashiro, Shunsuke Takeuchi, Kento Hama, Kentaro Kumagai, and Yuichi Jose but early in 2018, all crews in the franchise received a new member, extending the lineups to 6 people.

Seiya Konishi is the recent addition to the Autumn Troupe.

The Autumn Troupe has participated in four EP series: First (2017), Blooming (2017),  VIVID (2018) and BRIGHT (2019).

Brave Hearts (2018)

brave hearts

BRAVE HEARTS consisted on Makoto FurukawaKentaro KumagaiToshiki MasudaArthur Lounsbery and Ayumu Murase. The unit has a bright J-pop sound.

The unit was part of IDOL FANTASY smartphone game that stopped distribution in May 2019.

BRAVE HEARTS released two singles STORYBOOK FANTASIA and JUSTICE before the game was announced as being discontinued.

SHINE★彡 (2018 – 2019)


SHINE★彡 was a unit part of Op8♪ , idol raising smartphone game that launched in 2018 on iOS and Android.

The player is the chairman of a newly established record label. SHINE★彡 consist ofShoya Chiba (leader), Shohei Komatsu, Junta Terashima, Kentaro Kumagai, Kento Ito, and Yusuke Nagano. Kumagai plays Itsuki Reikei.

The game was short-lived, stopping distribution in 2019.


ASTRALAGUS consists of Masanori Kobayashi, Kentaro Kumagai, Jun Kasama and Yasuaki Takumi.

GANG×ROCK, is a music project created by Techno Art that mixes “delinquents” and “bands” in the same place.

GOALOUS5 (2019 -)


The group consisting of Kentaro KumagaiJunta TerashimaShugo NakamuraShohei Komatsu and Toshinari Fukamachi is to debut in 2019. 

GOALOUS5‘s concept is “that of a dark hero who tries to win the world by using his voice”. Additionally, each member dons a different “color”.


If there is something people know about Kumagai is that he has the right skills to host shows, no matter the format, and those skills are noticeable in several of the radio shows he has hosted so far as well as some of the A3! live broadcasts.

However, no matter how natural he is at hosting live broadcasts, his talent is not enough to command a rowdy group of guests.

On a couple of occasions, members of the Autumn troupe made such a mess that even when Kumagai attempted to take over and redirect the conversation back to where it should be – following the script -, nothing worked, leading to him getting frustrated, much to the other members’ entertainment.

Sawashiro was the cause of several moments in which the show became a complete disorganization to the point of everyone saying whatever they wanted and Kumagai being unable to do anything else but to laugh or become desperate as he could not proceed to the next corner.

Some other events he has been include Grandcrest and Idolm@ster SideM‘s and the same could be noticed about Kumagai, he has the potential to host shows and is an entertaining guest.


Designer in collaboration with LIVERTINE AGE

In 2017, Kumagai‘s collaboration with LIVERTINE AGE launched, and a zip parka and a pullover parka were available for sale on the site.

That was it for this month’s Seiyuu Digest.

Nadine Silva
Former The Hand That Feeds HQ reviewer (2014 - 2019). Rocker and passionate about a good bass line or low vocal, Nadine is now shining in a different team, rocking and dazzling in the IT industry.






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