Kappei Yamaguchi is one of Japan’s most recognizable voice actors, known for bringing some of anime’s most enduring characters to life. His best-known performances include Usopp in One Piece, Ranma Saotome in Ranma ½, Inuyasha in Inuyasha, Shinichi Kudo and Kaito Kid in Detective Conan, and L in Death Note.
Born in Fukuoka in 1965, Yamaguchi originally moved to Tokyo with ambitions of becoming a stage actor. His early work with the theatre company 21st Century FOX eventually led to voice-acting opportunities, and his breakthrough came when he was cast as Ranma Saotome in the 1989 anime adaptation of Rumiko Takahashi’s Ranma ½. The role established him as a leading voice performer and opened the door to decades of work in anime, animated films, games, dubbing and stage productions.
Yamaguchi has also received major professional recognition. In 2003, he won an individual voice-actor award at the Tokyo International Anime Fair, and in 2019 he received the Kei Tomiyama Award at the 13th Seiyu Awards.
Who Is Kappei Yamaguchi?
Kappei Yamaguchi is the professional name of Mitsuo Yamaguchi (山口光雄), while his stage name is written 山口勝平 in Japanese. He was born on May 23, 1965, in Fukuoka, Japan.
He is a Japanese voice actor and stage actor and is associated with his own entertainment production company, Gokū. His professional career has extended beyond conventional anime voice acting into films, video games, foreign-film dubbing, narration, theatre and other performance work.
Yamaguchi’s career is particularly unusual because he has maintained several major characters for decades. His work as Usopp, Shinichi Kudo and Kaito Kid has continued across television series, theatrical films and games, while Ranma and Inuyasha remain among the defining characters of his earlier career.
The official One Piece website describes Yamaguchi as the familiar voice of Usopp and notes that he has also continued working as a stage actor alongside his voice career.
Early Life and Career
Yamaguchi grew up in Fukuoka and developed an interest in performing from a young age. In an interview with Animate Times, he explained that he enjoyed performing at school and eventually moved to Tokyo because he wanted to become an actor. At that point, becoming a voice actor was not necessarily a clearly defined career objective for him.
After arriving in Tokyo, he joined 21st Century FOX, a theatre company led by veteran actor and voice performer Kaneta Kimotsuki. His initial focus was stage acting rather than animation.
Yamaguchi has explained that his transition into voice acting happened somewhat unexpectedly. Because the theatre company had connections to people working in animation, he was offered voice work. He described essentially being placed into a recording studio after working on stage and learning the craft through experience.
That theatrical background became an important part of his later style. Unlike performers who entered the profession exclusively through voice acting, Yamaguchi had already developed experience with physical performance, character interpretation and live theatre.
His major breakthrough arrived in 1989, when he was selected to play Ranma Saotome in Ranma ½. The official Ranma ½ website continues to list Yamaguchi as the voice of Ranma Saotome in the modern anime adaptation, demonstrating how strongly his performance has become associated with the character.
Voice Acting Career
The Breakthrough With Ranma ½
Ranma ½ was the role that changed Yamaguchi’s professional trajectory. He voiced the male form of Ranma Saotome, a teenage martial artist whose life is complicated by a supernatural transformation.
Yamaguchi’s performance had to balance action, comedy, romance and the character’s unusual gender-changing premise. The role demanded quick changes in emotional tone and became an early demonstration of his ability to play energetic young characters.
In a 2025 interview discussing the modern Ranma ½ adaptation, Yamaguchi recalled moving from Fukuoka to Tokyo at 19, spending several years performing with a theatre company and then receiving his opportunity as a voice actor. He described Ranma as a particularly important character because it was his first named role and effectively became the foundation of his voice-acting career.
Building a Career Across Anime
Following Ranma ½, Yamaguchi quickly became associated with a wide range of anime productions.
He voiced Tombo in Hayao Miyazaki’s Kiki’s Delivery Service, Mankichi Togawa and other characters in different productions, and Jin in Yu Yu Hakusho. He also appeared as Sai Saici in Mobile Fighter G Gundam, Takuya Enoki in Baby & Me, and other characters during the 1990s.
His ability to perform youthful, comic and highly expressive characters made him particularly valuable in shonen and comedy-oriented animation.
One of his most important long-term roles arrived in 1996, when he began voicing Shinichi Kudo in Detective Conan. He later became equally associated with Kaito Kuroba/Kaito Kid, allowing him to portray two characters who are central to the franchise’s mystery and detective stories. Official Detective Conan material continues to identify Yamaguchi with Kaito Kid and the Shinichi/Kaito side of the franchise.
Usopp in One Piece
Another defining chapter began in 1999, when Yamaguchi became the original Japanese voice of Usopp in One Piece.
Usopp requires a very different performance from Ranma or Shinichi Kudo. He is funny, nervous, imaginative and frequently exaggerated, but he also experiences some of the series’ most emotional moments.
The official One Piece character page identifies Yamaguchi as Usopp’s voice actor and describes Usopp as the Straw Hat Pirates’ sniper, a character who dreams of becoming a brave warrior of the sea despite his tendency toward fear and exaggeration.
Yamaguchi has remained with the character throughout the television anime and its extensive collection of theatrical movies and specials. The official One Piece website has also featured him extensively in interviews, fan events and behind-the-scenes programs.
Inuyasha
Yamaguchi’s next major character associated with Rumiko Takahashi was Inuyasha, the half-demon protagonist of the anime Inuyasha.
The character allowed him to move into a more dramatic role while retaining the energetic personality that had worked so well for Ranma. His performance continued in the later Inuyasha: The Final Act material and in the sequel Yashahime: Princess Half-Demon.
The connection between Yamaguchi and Takahashi’s characters has therefore lasted for decades, from Ranma to Inuyasha and their respective modern adaptations.
L in Death Note
Yamaguchi demonstrated another side of his range as L in Death Note.
Unlike Usopp or Ranma, L is quiet, eccentric and intensely analytical. His unusual speech patterns, physical mannerisms and detached personality required a considerably different vocal approach.
The role became one of Yamaguchi’s most internationally recognizable performances and helped demonstrate that his range extended well beyond comic protagonists. His credited performance as L is documented in the series’ cast records.
Most Famous Anime Roles
Usopp — One Piece
Usopp remains one of Yamaguchi’s signature performances. His voice is central to the character’s combination of comedy, insecurity and bravery.
Yamaguchi has also remained closely involved with the franchise outside the recording studio, appearing at One Piece events and contributing to official promotional programs. The official franchise website has repeatedly identified him as Usopp’s performer.
Ranma Saotome — Ranma ½
Ranma was Yamaguchi’s breakthrough named anime role and remains one of the characters most closely connected with his early career.
His return to the modern Ranma ½ adaptation more than three decades after the original series was particularly significant. The current official cast page continues to list Kappei Yamaguchi as Ranma Saotome.
Inuyasha — Inuyasha
Inuyasha gave Yamaguchi one of his most recognizable dramatic and action-oriented roles. The character’s combination of aggression, vulnerability and romantic conflict allowed him to explore a broader emotional range.
Shinichi Kudo — Detective Conan
As Shinichi Kudo, Yamaguchi voices one of the most important characters in the Detective Conan franchise. Shinichi is a brilliant teenage detective whose transformation into Conan Edogawa drives the central premise of the series.
Yamaguchi’s performance has continued for decades and includes the franchise’s numerous theatrical films.
Kaito Kid — Detective Conan / Magic Kaito
Yamaguchi also voices Kaito Kuroba, better known as Kaito Kid. The role is dramatically different from Shinichi but still requires a confident, playful and intelligent performance.
His dual association with Shinichi and Kaito Kid has become one of the most distinctive aspects of his career.
L — Death Note
L represents one of Yamaguchi’s most dramatic departures from his traditionally energetic roles. The character’s unusual personality and subdued delivery helped demonstrate the actor’s versatility.
Feitan — Hunter × Hunter
Yamaguchi also voices Feitan Portor in Hunter × Hunter. The character’s darker personality provides another example of his ability to work outside the youthful-comedy roles for which he first became famous.
Kappei Yamaguchi’s Notable Characters
| Anime / Project | Character | Year | Role Type |
|---|---|---|---|
| Ranma ½ | Ranma Saotome | 1989 | Japanese original voice |
| Kiki’s Delivery Service | Tombo | 1989 | Japanese original voice |
| Yu Yu Hakusho | Jin | 1992 | Japanese original voice |
| Mobile Fighter G Gundam | Sai Saici | 1994 | Japanese original voice |
| Detective Conan | Shinichi Kudo | 1996–present | Japanese original voice |
| Detective Conan / Magic Kaito | Kaito Kid / Kaito Kuroba | 1996–present | Japanese original voice |
| One Piece | Usopp | 1999–present | Japanese original voice |
| Inuyasha | Inuyasha | 2000 | Japanese original voice |
| The Twelve Kingdoms | Rokuta / Enki | 2002 | Japanese original voice |
| Death Note | L | 2006 | Japanese original voice |
| Persona 4 | Teddie / Kuma | 2008 | Japanese game voice |
| Hunter × Hunter | Feitan | 2011 | Japanese original voice |
| Persona 4: The Animation | Teddie | 2011 | Japanese original voice |
| JoJo’s Bizarre Adventure: Stardust Crusaders | Forever | 2014 | Japanese original voice |
| Yashahime: Princess Half-Demon | Inuyasha | 2020 | Japanese original voice |
| Odd Taxi | Eiji Kakihana | 2021 | Japanese original voice |
| Jujutsu Kaisen | Choso’s brother Kechizu | 2020 | Japanese original voice |
These are selected highlights rather than a complete filmography. His career contains hundreds of additional credits across television, films, games, OVAs and other forms of animation.
Movies, Television and Other Voice Roles
Yamaguchi’s work has never been restricted to television anime.
Animated Films
His film credits include Tombo in Kiki’s Delivery Service and numerous One Piece theatrical productions as Usopp. He has also performed Shinichi Kudo and Kaito Kid in many Detective Conan films.
His filmography includes One Piece Film: Strong World, One Piece Film Z, One Piece Film Gold, One Piece: Stampede and One Piece Film Red. Rotten Tomatoes lists Yamaguchi as Usopp in One Piece Film Red and One Piece: Stampede, alongside his extensive Detective Conan film work.
Video Games
Yamaguchi has also established a substantial career in games.
One of his best-known game performances is Teddie/Kuma in Persona 4 and its related animated and fighting-game adaptations. Official Persona 4 the Golden Animation material identifies Yamaguchi as Teddie’s Japanese voice actor.
He also voices Red XIII in Final Fantasy VII Remake, adding another major gaming franchise to his résumé. The Japanese voice performance is credited to Yamaguchi.
His game work demonstrates the same range found in his anime career, from comic mascot-like characters to action-oriented and dramatic roles.
A particularly notable upcoming project is Persona 4 Revival, where Sega has confirmed that Yamaguchi will once again provide Teddie’s Japanese voice. The game is scheduled for release in 2027, with the English performance provided by Laila Berzins.
Japanese Dubbing
Yamaguchi has also performed Japanese-language dubbing for international animation. His credits include Max in Japanese versions of A Goofy Movie and Mickey’s Twice Upon a Christmas.
He is also known in Japan for providing voices for characters such as Bugs Bunny and Garfield, demonstrating that his career extends beyond Japanese-produced animation. A 2021 cast biography for the animated project Magical Beast Sherbert specifically identifies him as the Japanese voice of both characters.
These should not be confused with his original Japanese anime roles. In One Piece, Ranma ½, Inuyasha and Detective Conan, Yamaguchi is performing the original Japanese character voice. In productions such as A Goofy Movie, his contribution is instead a Japanese-language dub of an internationally produced animation.
Live-Action and Stage Work
Although Yamaguchi is best known for voice acting, he has maintained connections with live performance throughout his career.
His background in theatre was instrumental in his development as a performer, and he has continued appearing in stage productions. He has also participated in live performance projects connected with anime and games.
His theatre experience has arguably contributed to the expressive quality that defines many of his best-known voice performances. In interviews, he has discussed the difference between stage acting and voice acting, noting that voice work removes the physical appearance of the performer and allows him to play characters that may be completely different from himself.
Awards and Recognition
Yamaguchi’s contribution to Japanese voice acting has received formal industry recognition.
Tokyo International Anime Fair Voice Actor Award
In 2003, Yamaguchi received an individual voice-actor award at the Tokyo International Anime Fair. His official Tokuma Japan profile identifies this as an important early career honor.
Kei Tomiyama Award
In 2019, Yamaguchi received the Kei Tomiyama Award at the 13th Seiyu Awards.
The award is particularly appropriate for an actor whose career has been built around long-term work across different areas of voice performance. The official Seiyu Awards page lists Yamaguchi as the recipient of the Kei Tomiyama Award, with his affiliation given as Gokū.
The recognition came after decades of work on major productions including Ranma ½, Detective Conan, One Piece, Inuyasha and Death Note.
Career Highlights
A breakthrough role that became a career foundation
Ranma Saotome was not simply an early credit. Yamaguchi has described the character as a particularly important part of his professional identity and the role that helped him establish voice acting as his main career.
Decades as Usopp
His performance as Usopp has continued through the long-running One Piece television series, films, specials, games and promotional projects. The official franchise continues to identify him as Usopp’s voice.
Multiple iconic characters in one franchise
His work as both Shinichi Kudo and Kaito Kid is another unusual career achievement. Few voice actors become so strongly associated with two major characters within the same long-running franchise.
Exceptional range
Yamaguchi can move from the comic energy of Usopp and Ranma to the quiet intelligence of Shinichi and L, the darker personality of Feitan, the emotional intensity of Inuyasha and the playful personality of Teddie.
A career beyond anime
His work includes Studio Ghibli animation, international dubbing, games, theatre and live events. This breadth helps explain why he has remained relevant across several generations of Japanese animation fans.
Why Is Kappei Yamaguchi So Recognizable to Anime Fans?
Kappei Yamaguchi is recognized by anime fans because his voice is attached to an unusually large collection of long-running and internationally successful characters.
For older anime audiences, he may immediately be associated with Ranma Saotome or Inuyasha. For One Piece fans, he is the unmistakable Japanese voice of Usopp. Detective Conan viewers know him as Shinichi Kudo and Kaito Kid, while Death Note fans recognize him as L.
The longevity of these performances is just as important as their popularity. Yamaguchi has continued playing several of these characters for decades, adapting his performances as the productions themselves have evolved.
His own comments about returning to Ranma ½ illustrate this longevity. He has acknowledged that his voice and acting have changed with age, while also viewing that evolution as part of his growth as a performer.
That combination of longevity, versatility and recognizable character work has made Kappei Yamaguchi one of the defining male voice actors of modern Japanese animation.
Frequently Asked Questions
Who is Kappei Yamaguchi?
Kappei Yamaguchi is the professional name of Japanese actor and voice actor Mitsuo Yamaguchi, born May 23, 1965, in Fukuoka. He is best known for Usopp, Ranma Saotome, Inuyasha, Shinichi Kudo, Kaito Kid and L.
What is Kappei Yamaguchi most famous for?
He is particularly famous for Usopp in One Piece, Ranma Saotome in Ranma ½, Inuyasha in Inuyasha, Shinichi Kudo and Kaito Kid in Detective Conan, and L in Death Note.
Is Kappei Yamaguchi the original Japanese voice of Usopp?
Yes. Yamaguchi is the original Japanese voice actor for Usopp in One Piece. The official franchise website lists him as Usopp’s voice actor.
Did Kappei Yamaguchi voice Ranma in the new Ranma ½ anime?
Yes. Yamaguchi returned as Ranma Saotome for the modern Ranma ½ anime adaptation. The official cast page lists him as Ranma Saotome.
Who does Kappei Yamaguchi voice in Detective Conan?
He provides the Japanese voices of Shinichi Kudo and Kaito Kid/Kaito Kuroba. His work as these characters extends across the television anime, films and related productions.
Is Kappei Yamaguchi the English voice actor for these characters?
No. Yamaguchi is primarily the original Japanese voice actor for these characters. English-language versions of One Piece, Detective Conan, Death Note and other productions use different performers.
What games has Kappei Yamaguchi voiced?
Among his notable game performances are Teddie in Persona 4, Red XIII in Final Fantasy VII Remake, and characters from several other major Japanese game franchises. Sega has also confirmed that he will voice Teddie in Persona 4 Revival.
