Kōsei Tsubokura is a Japanese voice actor and actor associated with Sony Music. He was born on January 7, 1997, in Tottori Prefecture, Japan. He stands 175 cm tall, has blood type B, and his hobbies include visiting hot springs and running marathons. He is also skilled in soccer and badminton.

Tsubokura is primarily known for his voice role as Jun Wakasa in the multimedia idol project UniteUp! He voiced this character in the first anime television series, UniteUp!, which aired in 2023, and reprised the role for its second season, UniteUp! -Uni:Birth-, which aired in 2025. For his work on these series, he is also credited with theme song and inserted song performances as part of the project's musical component.

Beyond anime voice acting, Tsubokura has also appeared in live-action drama and film adaptations. In 2023, he played the main role of Terashima Natsuki in the Japanese drama series Blue Sky Complex. The same year, he took on the supporting role of Suzuki Takeshi in the film Takumi-kun Series: The Dawn of the Long Tales.