Mas Oyama
, also known by his Korean name of Moon Jang-gyu (Hangul: 문장규; Hanja: 文章圭), is a South Korean martial artist in Japan. He is the master of Kyokushin karate and current "Kancho" (Director) of the , only faction of the International Karate Organization (IKO) founded by Mas Oyama (1923–1994).