Tomoichi Kubota was born in Shimochi Village, Tosa County (now part of Kōchi City), Kōchi Prefecture, on 13 December 1903. After graduating from Kobe Higher Commercial School, he became a teacher in Hiroshima Prefecture and was assigned to Kōchi Commercial High School in 1941. He was well respected as a warm-hearted teacher and served as principal from 1959 to 1965. He also attended the Kōchi Commercial School reunion until he was in his late 90s.

When asked about the secret of his health, he attributed it to regular walking since he was young and his wife’s cooking. He continued to live at his home in Kōchi City until he was over 100 years old. In 2008, he contracted pneumonia and spent the rest of his life in the hospital. When some of his students from his teaching days (in their 80s at the time) visited him at the hospital in 2010, he was in a wheelchair but in good spirits as they reminisced about those days.

He passed away on March 29, 2015 at the age of 111 years and 106 days. At the time of his death, he was the third longest-lived Japanese male.