Masutatsu Oyama (大山 倍達 Ōyama Masutatsu, July 27th, 1923 – April 26, 1994), more commonly known as Mas Oyama, was a karate master who founded Kyokushinkai Karate, considered the first and most influential style of full contact karate. He was born Choi Yeong-eui (Korean: 최영의 in Korea, Hanja: 崔永宜). A Zainichi Korean, he spent most of his life living in Japan and acquired Japanese citizenship in 1964. He is an alumnus of Waseda University in Japan.