[7] After graduating from Japan Women's University's affiliated high school, Kōchi worked as an office lady,[9] but she joined Toho through their "New Face" program in April 1953,[10] along with Akira Takarada, Kenji Sahara, Yū Fujiki, and Masumi Okada (who later moved to Nikkatsu).

[citation needed] One year after leaving Toho, Kōchi did her formal study of acting with Tsutomu Yamazaki and Kumi Mizuno and joined Haiyuza Theatre Company.

During her later years, she appeared as Toshiko Takahashi, a woman with Alzheimer's disease, in Wataru Seken wa Oni Bakari (渡る世間は鬼ばかり), with Kunihiko Mitamura.

Two days later, on 21 July, she made a guest appearance in a TBS Monday Drama Special, Enka Shōtarō no ninjō jiken nisshi (演歌・唱太郎の人情事件日誌).

[citation needed] Kōchi continued her hospitalisation until she died on 5 November 1998 at the Japanese Red Cross Medical Center in Hiroo, Shibuya from colon cancer at the age of 66.

[12] On 29 October, a week before her death, she was baptised into the Roman Catholic Church under her baptismal name of "Maria" by Father Masahiro Kondō of the Congregation of the Most Holy Redeemer.

[14] Due to Kōchi's roles in Catholic religious radio programs including Light of the Heart (心のともしび, Kokoro no Tomoshibi) and Taiyō no hohoemi (太陽のほほえみ), she was congratulated by Pope John Paul II with two awards in 1996.