Tomokazu Koshimura is a Japanese actor and voice actor born on May 22, 1979, in Saitama Prefecture, Japan. He is professionally affiliated with the talent agency Office Celeson. Standing at 171 cm, his blood type is B, and his known hobbies and skills include cooking, boxing, impersonations, and English conversation. Koshimura began his career as a member of the theater company Tokyo Celeson Deluxe before joining the Seinenza Theater Company.

Koshimura has an extensive career in live-action Japanese television dramas and films, with numerous guest roles and supporting appearances. His notable television credits include appearances in series such as Doctor-X, Death Note, the long-running series Aibou, and the drama special Olympiacos. In film, he is known for his role as Kōta Nakamura in the 2011 live-action feature GANTZ: PERFECT ANSWER, which is a sequel to the film Gantz based on the manga by Hiroya Oku. He also appeared in the 2018 film Aiaigasa.

Although primarily known for his on-screen work, Koshimura has also taken on roles in voice acting. One of his most prominent voice roles is Saji in the dark fantasy anime series Dorohedoro. He was announced as part of the cast for the show's second season, which premiered in April 2026, voicing a member of the Jujime organization, also known as the Cross-Eyes. While his anime voice roles are not numerous, his casting in Dorohedoro alongside well-known voice actors marks a significant achievement in this field. His professional profile highlights a versatile career spanning both live-action performance and voice work in Japanese entertainment. As an actor, he is sometimes associated with the nickname or characteristic of having naturally curly afro-textured hair.