Often regarded as the strongest karate style, Kyokushin (極真) is a style of stand-up, full contact karate, founded in 1964 by Korean-Japanese Masutatsu Oyama (大山倍達 Ōyama Masutatsu). Kyokushin is Japanese for "The Ultimate Truth." Kyokushin is rooted in a philosophy of self-improvement, discipline and hard training. Its full contact style has had international appeal (practitioners have over the last 40+ years numbered more than 12 million).
http://en.wikipedia.org/wiki/Kyokushin
http://www.kyokushinkaikan.org/en/
http://www.mas-oyama.com/english/