Complex sentence: The first was Seigo Okamoto who founded the Daito-ryu Roppokai, whose own interpretation of aiki and minimal movement throws have proved very popular and has a great following abroad, especially in USA and Europe.
Split into simpler sentences: The first was Seigō Okamoto (岡本 正剛 "Okamoto Seigō", born 1925) who founded the, whose own interpretation of "aiki" and minimal movement throws have proved very popular. The organization has a great following abroad, especially in the United States and Europe.