Kumaji Yoshimoto was born in Yamaguchi-ken, Japan, on August 29, 1886. He was converted to Christianity while a student at Waseda University. After graduation from Waseda, he attended Stanford University for about three years and worked as a landscape gardener until World War II broke out. His first wife bore him two daughters, Kiyoko and Michiko. After her death, Yoshimoto married again. He and his second wife, Misao, had a daughter, Dorothy. Misao had another daughter, Emiko, from a previous marriage.

After his marriage, Yoshimoto devoted much of his spare time witnessing to Japanese immigrants. Although he was a board member of the Centenary Methodist Church, he did not attend church often, but he devoted much time witnessing to fellow immigrants. Gunsaku Kuwahara, who Yoshimoto knew through the Shimobe-kai—a group of people who supported Dr. Teikichi Sato—invited him to the Los Angeles Holiness Church. Yoshimoto reluctantly came, but as a result, his faith was renewed. He recommitted his life to Christ and was baptized by Sadaichi Kuzuhara. In 1937, Yoshimoto began the ground work for the West Los Angeles Holiness Church through meetings held at various homes with Sentaro Ginoza.

With the outbreak of World War II, Yoshimoto was first sent to the Santa Anita Assembly Center and then to the Rohwer Relocation Camp in Arkansas. He served as a block manager in camp. Incarceration afforded him many opportunities to share his faith with other internees. After a brief stay in Chicago, he returned to Los Angeles in 1949 and started regular prayer meetings.

On July 17, 1955, after dedication of the church building, Yoshimoto was appointed as a lay-preacher. He was sixty-nine years of age at that time. In 1965, he retired after a faithful ten year ministry at the West Los Angeles Holiness Church. Kumaji Yoshitomo passed away in peace on September 15, 1981, at the age of ninety-five.