Seigo Yamaguchi (8th Dan) was born in Fukuoka, Kyushu in 1924. As a 19-year old student, he joined the marines and underwent training in a kamikaze submarine unit. In 1960, when he was 26, he was introduced to Aikido’s founder, Morihei Ueshiba. He was moved by Ueshiba’s aikido and began to train with him.

After a number of years of training he began to teach regularly at the Aikikai Hombu dojo, and fulfilled his duty to, in its early years, spread aikido beyond the borders of Japan. In 1958 Yamaguchi Sensei was sent to Burma to train the national army in Aikido. In 1961 he returned to Hombu as a senior Aikido instructor.

In the 1960s and 70s Yamaguchi’s aikido began attracting people outside of Japan. It was in this manner that Frenchman Christian Tissier came to train with him for a number of years. Starting in 1977, Yamaguchi Sensei regularly gave seminars outside of Japan, continuing to do so until 1995. In addition to his courses at the Hombu dojo, he also taught at various universities in Tokyo.

Yamaguchi Sensei died on January 24, 1996 in Tokyo, after being active in Aikido for more than 45 years.