Riho Sugiyama is a Japanese voice actress from Hokkaido, born on December 31. She is affiliated with the talent agency Mausu Promotion. Her journey into the industry began after high school when she enrolled in the Sapporo Manga, Anime, & Voice Actor Vocational School to train for her career. She started her professional activities in 2013 with the agency Yu-rin Pro, and in 2018, she transitioned to her current agency, Mausu Promotion.

Sugiyama's early career consisted of various supporting roles in anime television series. In 2017, she voiced Urara Suidobashi in Atom: The Beginning and Tadashi Konparu in Kenka Bancho Otome: Girl Beats Boys. The following year, she landed her first lead role as Tanis in the 2018 anime series Creatures Family Days. That same year, she also voiced Tarua in the series Conception. Her role count continued to grow with parts in major productions such as JoJo's Bizarre Adventure: Golden Wind, where she played Anita, and the role of Miriam in Ulysses: Jeanne d'Arc and the Alchemist Knight.

The year 2020 marked a significant turning point in her career when she was cast as Minare Koda, the protagonist of the anime series Wave, Listen to Me!. This role was particularly demanding, as her character delivered a massive amount of dialogue, sometimes accounting for 60 to 70 percent of an episode's script. Her powerful and dynamic performance as the brash and struggling radio personality garnered widespread attention and critical acclaim. For this breakout role, she was nominated for Best VA Performance (JP) at the 5th Crunchyroll Anime Awards.

In 2021, her impactful performance was formally recognized by the industry when she was one of the recipients of the Best New Actress Award at the 15th Seiyu Awards. Following this recognition, her career continued to flourish with a steady stream of roles. She voiced Rosary in I've Been Killing Slimes for 300 Years and Maxed Out My Level, and Henrietta Penrose in the acclaimed series 86. Her versatility is evident in the range of characters she has played, from the historical figure Henry Stafford, Duke of Buckingham in Requiem of the Rose King to characters like Chino Hamura in Gal-gaku. II: Lucky Stars and Arumi Ashimine in Tsugumomo2.

Throughout the 2020s, Sugiyama has maintained a prolific output. In 2022 alone, she took on roles including Yori-chan in On Air Dekinai!, Tsumugi Kume in 3 Seconds Later, He Turned Into a Beast, Jessica Schwarz in Vermeil in Gold, and Rakko-shun in the original net animation Zetsumetsu Kigu-shun. She has also been active in the horror genre, voicing Kazuko Morinaka in Junji Ito Maniac: Japanese Tales of the Macabre. Her work extends beyond television anime to include original net animations like Ghost in the Shell: SAC_2045 as Opeko and video game voice acting in major titles such as Final Fantasy XIV and Guilty Gear Strive. More recently, she has continued to expand her repertoire with roles in series like Necronomico and the Cosmic Horror Show as Miko Kurono and Rinkai! as Kinusa Takamatsu.