Ryōko Jūni is a Japanese female voice actor born on July 29, 1999, in Kanagawa Prefecture. She is affiliated with the talent agency Stardust Promotion. Her interest in becoming a voice actor began during her high school years when she became a fan of voice actors. To pursue this career, she attended a voice actor training school for about two years on a weekly basis while simultaneously enrolled in a junior college. After graduating from both around the same time, she joined her current agency.

Jūni made her debut in television animation in 2021 with a role as Machiko in the series "大正オトメ御伽話" (Taisho Otome Otogibanashi). Her first major leading role came in 2022 when she was cast as Lettuce Midorikawa, also known as Mew Lettuce, in the anime series "Tokyo Mew Mew New". She reprised this role for the series' second season in 2023 and also voiced the character in the related web anime "ぷち！東京ミュウミュウ にゅ〜♡". Her other voice roles in animation include a classroom friend in "CUE!" in 2022 and a high school student in the 2025 web anime "章鱼噼的原罪" (Takopi's Original Sin). She also provided her voice for the 2022 animated film "怪盗クイーンはサーカスがお好き" (Kaito Queen wa Circus ga Osumi) as Iwasaki Mii.

In addition to animation, Jūni has voiced characters in several video games. Her game credits include角色 in "Monster Strike" (as Renki), "World Flipper" (as Hoshino Mikoto), and "Black Knight and White Devil". In 2024, she joined the cast of "Azur Lane" as Portsmouth Adventure and also voiced a character in "Blue Archive".

Beyond voice acting, Jūni is a member of the voice actor unit Smewthie, through which she has participated in music and television appearances, including on the program "Oha Suta". She is also active in stage performances and reading aloud theater productions, taking on roles in works such as the stage play "少年秘密倶楽部 - 零 -" (Shonen Himitsu Kurabu -Zero-) in 2023 and various reading dramas. She hosted her own radio program, "十二稜子のラジラブ!" (Jyuni Ryoko no Rajirabu!), on the cultural broadcasting station in late 2024. Her hobbies include singing, playing mahjong, and reading aloud, while her special skills are playing soft tennis and maintaining a positive outlook.