Seigo Yamaguchi (山口 清吾 Yamaguchi Seigo, 1924–1996) was a 9th-dan aikido instructor and important teacher in the Aikikai. According to Mitsugi Saotome, before he was sent to Burma in 1958, he was the most prolific teacher at Aikikai Hombu Dojo.
Yamaguchi was born April 13, 1924, in Fukuoka, Japan. After his early education, he entered the navy, where he was eventually to carry out a Kamikaze suicide mission, but was saved by the end of World War II. He was introduced to Morihei Ueshiba in 1950, and entered the Aikikai in 1951. In 1958 he was sent to Burma to teach aikido to the army. Beginning in 1961 he again taught at the Aikikai Hombu Dojo; he also taught at his own dojo and at Meiji University.
- Nanaura, Fuyuo; Pranin, Stanley (1997), "Interview With Seiichi Sugano", Aikido Journal, 112, retrieved April 12, 2012
- "Seigo Yamaguchi: In memoriam", Aikido Journal, 108, 1996, retrieved April 15, 2012
- Pranin, Stanley (1991), "Interview with Mitsugi Saotome (1)", Aiki News, 89, retrieved April 16, 2012
- Interview with Seishiro Endo Archived 2012-09-20 at the Wayback Machine
- Interview with Takeda Shihan
- Biography of Christian Tissier Shihan
- "Timeline". Yamaguchi Dojo.
- "Bio". Yamaguchi Dojo.
- The Encyclopedia of Aikido. Aikido Journal. Retrieved April 12, 2012.