Yonehara was born in Kamou, Ohara, Shimane Prefecture, on 2 March 1892 as a farmer’s daughter. As was common for country girls at the time, she was schooled up until fourth grade. To support her family, she took a leave of absence from the school and worked as a babysitter. She enjoyed maths and reading, and taught herself to read kanji characters.
Yonehara later finished her education, and continued her job until her marriage. She later gave birth to five children, all of whom she outlived; two of them died young, and the remaining three lived to be octogenarians.
After her marriage, Yonehara spent lots of time cooking, never serving pre-packaged foods. She was widowed at the age of 69, after which she moved in with her eldest son and assisted in raising his children. She enjoyed teaching maths, and was often involved in events at her grandchildren’s school. On Sundays, she would walk a long distance to her husband’s grave and to a Nazarene church.
In her later years, Yonehara lived in a hospital, and was considered important to the staff; she often had lunch at a nearby noodle shop.
On 16 September 1998, aged 106, Yonehara became the oldest living person in Shimane Prefecture following the death of 107-year-old Yoshikazu Yamane. In April 2002, she broke the record of Sada Hata to become the prefecture’s oldest resident ever.
Yonehara died in Izumo, Shimane, on 4 January 2005 at the age of 112 years, 308 days. She was succeeded as Shimane’s oldest living person by Kiyo Okuna (1896 – 2006). She held the prefectural record for almost 13 years, until her age was surpassed by Kitsuyo Yamamoto in January 2015.