Born in 1830 as the eldest son of Yoshii Sahei in Nakamura, Yamabe-gun, Uesa Province (Togane City, Chiba Prefecture).

　He was adopted by Shunsuke Seki, a Confucian scholar, and entered the medical school of Taizen Sato in Sakura, where he practiced medicine. He practiced medicine in Choshi, but at the suggestion of Goryo Hamaguchi, he studied Western medicine under Pompe in Nagasaki.

　Later, he was invited by the Tokushima clan to become a samurai doctor, and during the Boshin War, he was active as the president of the Ou Branch Hospital, and devoted himself to the establishment of the Tokushima Medical School. After returning to Tokushima Prefecture, he returned to Tokushima and opened a clinic at the site of Higashi Goten (present-day Joto High School, Tokushima-machi 1-chome) and devoted himself to local medical services.

　After the golden wedding celebration of Mr. and Mrs. Kansai, he decided to pioneer Hokkaido, which was attracting attention as a necessary land for Japan's industrial development. His fourth son, Matakazu, was already 70 years old at the time, and was enrolled in Sapporo Agricultural College. He pioneered the Ishikari Tarukawa Farm and settled in Toman, Tokachi Province, in 1902 (35th year of Meiji) at the age of 72.
He formed Sekizen-sha, a company that sought a pioneering policy of cultivating his own farmland at Ninomiya Farm, which was managed by Takachika Ninomiya. He also deepened his friendship with Tokutomi Roka, sympathized with Tolstoy's ideas, and aimed to build an ideal farming village.