In 1965, Bluming became the first non-Japanese in being awarded the 6º dan in karate from Masutatsu Oyama. This decision was controversial enough among Asian karatekas to force Oyama to put a challenge in a magazine, challenging any of them to a fight against Bluming in a boxing ring and promising to strip him from his black belt if the Dutchman lost. Oyama was so confident that he also promised a hefty bounty and swore to retire himself from the Kyokushin school.
In 1965, Bluming became the first non-Japanese to receive a 6º dan in karate from Masutatsu Oyama. This decision sparked controversy among Asian karateka, leading Oyama to issue a challenge in a magazine, inviting any of them to fight Bluming in a boxing ring and threatening to strip him of his black belt if he lost. Oyama was so confident that he also offered a substantial reward and vowed to retire from the Kyokushin school.