Mihara made her debut as a teenager in the 1979 television series Kinpachi-sensei, and began a singing career in 1980.

[5] Mihara remained involved in racing—particularly the JGTC's successor Super GT—after entering politics, serving as the secretary general of the Liberal Democratic Party's Parliamentary League for Motorsports.

[6] Mihara underwent treatment for cervical cancer later in her life, and established a nursing home in March 2010 prior to her political debut.

[1] Mihara ran in the House of Councillors election in July 2010 as a proportional candidate of the Liberal Democratic Party[7] and won, campaigning on her experience with women's health issues.

[11] In March 2015, when speaking about dealing with tax evasion she urged Prime Minister Shinzō Abe to promote hakkō ichiu, a slogan meaning "the world under one roof".