Mayumi Oka is a Japanese actress, voice actress, and singer affiliated with the talent agency Horipro Booking Agency. Born on March 7, 1956, in Tokyo, she is also known by her stage names 岡まゆみ and her birth name, Mayumi Igarashi. Information about her early education indicates she withdrew from the Women's College of Art.

Oka's involvement with the anime series Manga Hajimete Monogatari is as a performer of its theme music. She sang the third opening theme song for the long-running educational program, which aired from 1978 to 1984. While she is credited as a voice actor, her role in this specific series was as a musical performer rather than a voice for one of its animated characters.

Her career in the entertainment industry is extensive, with her primary focus being on live-action television dramas and films. She has been active since at least the late 1970s, with early acting credits including the 1977 drama series Chi no Kusari. Over the following decades, she has built a substantial resume of guest and recurring roles in numerous Japanese television series. Notable appearances include roles in the drama series Style! in 2000, Trick 3 in 2003, a guest spot in the 2014 series Hero 2, and a role in the 2022 Netflix drama金魚妻. Her work spans across various networks and popular long-running franchises such as相棒 and 遺留捜査.