Biographie

As of March 2006, he is tied with Megumi Hayashibara as the third most prolific voice actor in Japan, behind second ranked Shinichirô Miki and top ranking Takehito Koyasu, respectively.

Does dubbing voice of Kyle from South Park.

Hobbies includes climbing and computers.

Recently he has taken on different roles such as L in Death Note and Hugh in Kiba which are serious characters with a lower voice range. Hugh (in Kiba) was an exception in that it is not only an adult role but also a villain.

Many, if not most of Yamaguchi's voice roles are teenagers or even younger boys. He is well-known for his ability to perform high-pitched, "young" voices. This is especially noticeable in BL dramas/games. His characters are also generally straightforward-minded, sometimes simple-minded, humorous and easily excitable but usually "good" characters.