Mayumi Sako is a Japanese actress and voice actress born on January 13, 1978, in the Setagaya ward of Tokyo. She was raised in a family of performers; her father, Masato Sako, was an accomplished actor and voice actor, and exposure to his work from a young age inspired her interest in the performing arts. During her middle school years, she actively participated in her school's theater club.

After graduating from Kanto International High School, Sako pursued formal training, joining the Bungeiza Training Institute in 1997. She became a full member of the prestigious Bungeiza theater troupe in 2002, a position she held until 2017, when she departed to sign with the talent agency Fukuda & Co., marking a new phase in her career focused more extensively on voice work. Her career is distinguished by a high degree of versatility, encompassing stage performance, narration, and extensive work in dubbing foreign films and television series, in addition to anime and video games.

Sako is particularly celebrated for her work in Japanese dubbing, where she is the regular voice provider for several major international actresses, including Scarlett Johansson, Rachel McAdams, Noomi Rapace, Jessica Chastain, and Jill Flint. Notable dubbing credits include Scarlett Johansson's roles in films such as Iron Man 2 and Lucy, and Rachel McAdams's performances in the Sherlock Holmes film series.

In anime, Sako has built a substantial portfolio of work. Among her notable roles are Rokuro Sakuragawa in In/Spectre and its sequel, and Mayumi Yamaguchi in Persona -trinity soul-. She has also been cast in roles within the Precure franchise, such as in Healin' Good Pretty Cure and Go! Princess Precure. Her role as Arnheid in the second season of Vinland Saga garnered significant attention and critical acclaim for her powerful and emotionally resonant performance. Reviewers praised her ability to convey the character's profound anguish with a deep sense of humanity, with each sigh and sob carrying the weight of immense suffering. Her other anime roles include Isabelle Müller in Great Pretender and Meguro in the web anime Blade of the Immortal. She also voiced Drolta Tzuentes in the Japanese dub of Castlevania: Nocturne.

Her work also extends to video games, where she is known for voicing Helena Harper in the Japanese version of Resident Evil 6 and Vice in The King of Fighters XIV.