Riku Hagiwara is a Japanese actor born on February 28, 1999, in Saitama Prefecture. While he is primarily known as a live-action film and television actor, his career includes voice acting work in animation. He began his entertainment career as a child actor in 2008, initially appearing in a commercial for Lego. His early television work included roles in dramas such as Monster Parent and Tomika Hero Rescue Force. Over the following years, he built an extensive filmography with supporting and lead roles in numerous projects, including the drama 3 Nen A Gumi and the film 12 Suicidal Teens. He graduated from Yubunkan High School and is represented by the agency TopCoat.

As a voice actor, Hagiwara is confirmed to have one major anime role. He provides the lead voice for the character Keitarō Obinata in the original animated feature film A New Dawn, which is scheduled for release in 2025. The official English title of the film is A New Dawn, and its Japanese title is Hanarokusho ga Akeru Hi ni. In the film, he voices the second son of the Obinata Fireworks Shop, who struggles to complete a fantastic fireworks display in place of his missing father. This film is directed by Japanese painter Yoshitoshi Shinomiya. His casting for this role was announced alongside Kotone Furukawa, a young actress who voices the female lead. His performance in this film represents his sole voice acting credit in animation as documented in major film and television databases.

Throughout his career as a live-action actor, he has received several awards and nominations. He won the award for Emerging Actor and the Most Popular Actor Couple award at the Weibo Account Festival in 2022. In 2024, he received the Elle Cinema Rising Star Award. More recently, in November 2025, he won the Best New Actor award at the 17th Japan TAMA Film Awards.