Sei Hiraizumi is a Japanese actor and voice artist with a career spanning over six decades, primarily known for his extensive work in live-action television and film. He was born on June 2, 1944, in Aichi Prefecture, Japan. His career in entertainment began in 1964 when he joined the Daiei Film company. After the studio's bankruptcy, he transitioned to television, becoming a familiar face in numerous police and samurai dramas, often cast as a villain. In the mid-1980s, he adopted the stage name Sei Hiraizumi and his roles gradually shifted towards more fatherly and everyman characters, solidifying his status as a beloved supporting actor.

While his primary body of work is in live-action, Hiraizumi has also contributed his distinctive voice to animated projects. In the 2015 animated film The Case of Hana & Alice, a prequel to the 2004 live-action film Hana and Alice, he voiced the character Kenji Kuroyanagi, the father of the protagonist Alice. This role connected him to the broader body of work by director Shunji Iwai, who also wrote and directed the original live-action film in which Hiraizumi appeared. He later took on a voice role in another high-profile animated film, Weathering With You (2019), where he played Detective Yasui, a calm and persuasive police officer.

Throughout his long career, Hiraizumi has built a reputation for versatility, appearing in a wide array of genres from period dramas to science fiction and family stories. His work in animation, though a smaller part of his overall filmography, adds to his diverse body of work and demonstrates his enduring presence in Japanese popular culture. His contributions to the film industry were recognized with a Special Award at the 49th Hochi Film Awards in 2024.