Ryou Hirohashi is a veteran Japanese voice actress born on August 5, 1977, in Niigata Prefecture. She is affiliated with the talent agency Aoni Production. Before pursuing voice acting, Hirohashi graduated from Ryukoku University in Kyoto, a decision influenced by her family's background operating a Buddhist temple. Her interest in the profession was sparked during junior high school after listening to a radio show hosted by a voice actor. She went on to train at the Aoni Juku training school in Osaka, graduating as part of its 16th class, and made her debut in 2002 with a small role in the anime Aquarian Age: Sign for Evolution. She also holds a certification as a junior high and high school Japanese language teacher.

Hirohashi's career is distinguished by her versatility in voicing both young girls and young boys. Her first major and most enduring role came in 2003 when she was cast as Miles "Tails" Prower in the anime Sonic X, a character she has continued to voice in numerous Sonic the Hedgehog video games, films, and other media for over two decades. This role established her as a prominent figure in the industry and connected her with a global audience.

Following her debut, Hirohashi secured a series of high-profile roles that showcased her range. In 2005, she began voicing Alice Carroll in the serene and critically acclaimed Aria anime series, a role she has reprised for numerous sequels and films, including Aria the Avvenire, Aria the Crepuscolo, and Aria the Benedizione. In 2007, she delivered a memorable performance as Kyou Fujibayashi in the emotional drama Clannad and its sequel Clannad After Story, a character known for her tsundere personality. That same year, she also began voicing Chōji "Marucho" Marukura in the long-running Bakugan Battle Brawlers franchise. Other significant recurring roles from this period include Koyuki Azumaya in Sgt. Frog and Aoi Yamada in the Wagnaria!! (Working!!) series.

In more recent years, Hirohashi has remained highly active, taking on roles in major franchises. Since 2016, she has voiced the character Minoru Mineta in the globally popular My Hero Academia series, including its several sequel seasons and animated films. She also voices Luna in the Pretty Guardian Sailor Moon Crystal series and its subsequent films, Sailor Moon Eternal and Sailor Moon Cosmos. Her filmography extends to a wide array of other roles, such as Soyo Tokugawa in Gintama, Hina Sorasaki in Blue Archive the Animation, and Onion in Pokémon: Twilight Wings.

Beyond anime, Hirohashi has an extensive career in video game voice acting. In addition to her long-running role as Tails, her game credits include Kanon Daiba in the God Eater series, Shirley Fennes in Tales of Legendia, Pandoria in Xenoblade Chronicles 2, and Jessica and Shaw in Arknights. She was also briefly a member of the seiyū unit "MORE PEACH SUMMER SNOW" alongside Chiwa Saitō, Mamiko Noto, and Haruna Ikezawa. As of 2025, Hirohashi continues to be an active and sought-after voice talent in the Japanese entertainment industry.