Ryoko Yui, also known as Ryoko Yuui, is a Japanese actress and voice performer born on August 10, 1976 in Tokyo, Japan. She is represented by the talent agency Box Corporation. Her career encompasses both live-action television dramas and voice acting for anime.

Yui is recognized in the anime industry for several supporting roles. She is the voice of Yoko Sakaki in the series Yu-Gi-Oh! Arc-V. Yoko Sakaki is the mother of the protagonist, Yuya Sakaki, and was formerly the leader of a biker gang known as the Maiami Queens. Additionally, she voiced the character of Niko's Mother in the 2024 film adaptation of Cells at Work!.

Beyond anime voice work, Yui has an extensive career in Japanese live-action television. Her filmography includes roles in popular drama series such as Code Blue, Kamen Rider W, Kamen Rider Kiva, Galileo, and My Dangerous Wife. She also appeared in the 2017 film Girls in Trouble: Space Squad Episode Zero. Her performance history includes a wide range of television dramas from the 1990s through the present day.