Asai started training under aikido's founder Morihei Ueshiba aged 13, at the Hombu dojo in Tokyo, and continued during his studies at Meiji University. He was sent to Germany by Kisshomaru Ueshiba in 1965 to teach aikido, and has lived in the country ever since. His first occupation was to teach aikido to policemen in Münster, and he now runs a school in Düsseldorf.
In the early days of German aikido, Asai clashed with the Deutscher Judobund (DJB) over whether his art should be included under their organisation. In this, he was opposed by Gerd Wischnewski, another student of Ueshiba, who was also a prominent member of the DJB. Although the DJB retained an aikido division, Asai remained independent of them and continued to operate as part of the Aikikai. He retains the German trademark on the term "Aikikai."
- Aikido Journal entry for Asai Archived 2011-08-03 at the Wayback Machine
- "Aikikai Germany entry for Asai". Archived from the original on 2012-09-24. Retrieved 2012-03-13.
- Sonntags-Post: Mecca of Aikido (German source) Retrieved March 6th 2012
- Homepage of german Aikido-Club Siegburg (German source) Retrieved August 8th 2012
- Freiberg: A turn for the better (German source) Retrieved March 6th 2012
- Black Belt Magazine, March 1969, Two factions spur aikido growth as DJB and Asia battle, p10
- Deutsches Patent- und Markenamt Archived 2007-06-22 at the Wayback Machine