Mariko Suga was born on 28 November 1953, in Shimizu, Shizuoka Prefecture, where her family ran a food wholesale business.

She attended Shimizu Higashi High School and was a member of its archery club.

During this time, she met and soon married Yoshihide Suga, who was her sister's co-worker, also working as a secretary to Hikosaburo Okonogi.

[1] Yoshihide Suga subsequently became a Yokohama city councilman in 1987, a member of the House of Representatives in 1996 and rose to prominence as the long-serving Chief Cabinet Secretary under Prime Minister Shinzo Abe from 2012.

Yoshihide Suga was appointed Prime Minister to succeed Abe in September 2020 and served until October 2021.