Ryoko Tanaka is a Japanese voice actress from Tokyo, born on July 28, 1973. She began her career in 1996 after graduating from the Japan Narrator Acting Institute. Throughout her career, she has been affiliated with several talent management agencies, including ARTSVISION, Office Mori as a trainee, and Pro-Fit, before eventually becoming a freelancer.

Tanaka has built a substantial portfolio of voice roles across television animations, original video animations, and video games. One of her well-known roles is Yuiko Kurugaya in the anime series Little Busters! and its related adaptations, including the crossover series Kaginado. Another significant role is Hikari Kuroda in the series School Days. She also voices Yumiko Sakaki in the Grisaia series, which includes The Fruit of Grisaia, The Labyrinth of Grisaia, and The Eden of Grisaia.

Her work in anime includes a variety of other characters. In 2008, she voiced Mei Isayama in Ga-Rei -Zero- and Kan'u in the Koihime Musō series. The following year, she was cast as Nagi Sakai in Asura Cryin'. In 2010, she played Yahiro Iokibe in the series Yosuga no Sora. Her role as Toka Nishikujo in the anime adaptation of Rewrite began in 2016, and she reprised this character for Kaginado in 2021.

In addition to her anime work, Tanaka has an extensive list of credits in video games. She has voiced characters in major titles such as Little Busters! and Rewrite, both originally visual novels by Key. She also contributed her voice to games like the Ys series, SHUFFLE! ON THE STAGE, and the School Days-related games L×H and Island Days. Her career demonstrates a strong and recurring collaboration with the visual novel brand Key, having played significant roles in several of their game adaptations.