Mantarō Koichi is a Japanese actor and voice performer born on February 15, 1969, in Osaka, Japan. While his primary career has been in live-action film and television, he has also established a significant body of work in voice acting for anime and video games. He is affiliated with the theatrical company Gekidan M.O.P.

In the world of voice acting, Koichi is best known for his long-standing association with the video game developer SNK. He provides the Japanese voice for the character Robert Garcia in the fighting game series The Art of Fighting and The King of Fighters. He is also recognized for voicing the character Galford Weller, a ninja from the United States, in the Samurai Spirits series, also known as Samurai Shodown. This role included his work in the 1999 original video animation Samurai Spirits 2: Asura Zanmaden, an anime adaptation that featured the same voice cast as the games.

Beyond his video game work, Koichi has taken on roles in several anime titles. In the series Wave, Listen to Me!, he voiced the character Katsumi Kureko. He also appeared in the live-action Rurouni Kenshin film series, playing the role of Toshiyoshi Kawaji in both Rurouni Kenshin Part II: Kyoto Inferno and Rurouni Kenshin Part III: The Legend Ends.

Although his voice roles are notable, the majority of Koichi's acting credits are in live-action productions. He has appeared in numerous television series, including Unmet: A Neurosurgeon’s Diary and Cinderellas of Midsummer. His filmography also includes roles in major films such as the 1998 horror classic Ring and the 2020 disaster drama Fukushima 50. This extensive work in live-action, alongside his recurring voice roles for SNK, defines his career as a versatile actor who moves between on-screen and voice-over work.