Soeno is currently the director of The World Karate Association Shidokan, headquartered at Shizuoka-ken, Japan.

TV Asahi requested a player from Kyokushin in February, 1969, and Masutatsu Ōyama elected Soeno and Terutomo Yamazaki to enter the competitions.

Kyokushin was planning to hold the First All-Japan Full Contact Karate Championships (AJFCKC) at the Tokyo Metropolitan Gymnasium in September, 1969.

The rules were simple: It was a foul to use a hand or elbow to the face and to attack a man's vital point.

Although had distanced himself from the Kyokushin Kaikan, he continued to have personal friendship with Mas Oyama, and the two would often meet at the sauna in Ikebukuro.

When Mas Oyama passed away, Soeno had rushed to the Kyokushin headquarters and started crying on the spot.