Masutatsu "Mas" Oyama (1923-1994) was a Korean-born Japanese karate master who founded Kyokushin karate and built the International Karate Organization Kyokushinkaikan, one of the largest karate organizations in the world.

Did Mas Oyama really fight bulls?

He gave bull demonstrations, one of which was filmed, but his former students have said the filmed fight was staged, and many popular accounts come from a manga that invented episodes. The claimed count of 52 bulls is not documented.

Who succeeded Mas Oyama?

Shokei Matsui was named successor under a will that Oyama's family contested and the Japanese courts later ruled invalid. The organization split into several rival Kyokushin groups.

When did Mas Oyama die?

He died of lung cancer in Tokyo on 26 April 1994, aged 70.

Mas Oyama, 1923–1994: The Founder Who Built Kyokushin, and the Split That Followed

Mas Oyama turned one hard-contact karate dojo in Tokyo into what his organization called the largest karate body in the world, by picking branch chiefs for their ability to sell the style as much as to fight in it and sending them abroad to build. He died in Tokyo on 26 April 1994, aged 70. Within months his organization had begun to split over his succession, and Kyokushin karate is today taught by several rival international organizations. His life is a case study in both halves of the founder’s problem: how to scale, and what happens after.

Name: Masutatsu Oyama; born Choi Yeong-eui
Born: 27 July 1923, Korea (then under Japanese rule), in the area of present-day Gimje, North Jeolla Province
Died: 26 April 1994, Tokyo, aged 70, of lung cancer
Art: Kyokushin karate
Trained under: The Funakoshi family (Shotokan); So Nei-chu (Goju-ryu); Kōtarō Yoshida
Founded: His first Tokyo dojo (1953); the International Karate Organization Kyokushinkaikan (1964), with its headquarters in Ikebukuro
Key books: What Is Karate? (1958); This Is Karate (1965); Vital Karate (1967); The Kyokushin Way (1979)

From Korea to Japan

Oyama was born Choi Yeong-eui in Korea, then part of the Japanese Empire, and spent part of his childhood in Manchuria. In March 1938, at fifteen, he moved to Japan, following an older brother. He trained in Shotokan karate under the Funakoshi family and in Goju-ryu under So Nei-chu, a fellow Korean from his home province, and reportedly called the jujutsu teacher Kōtarō Yoshida the greatest of all his teachers.

The legends, and what can be checked

Oyama’s reputation rests on three famous stories. He spent long periods training alone in the mountains, reportedly fourteen months on Mount Minobu and eighteen on Mount Kiyosumi. He fought bulls; his students later put the lifetime count at 52. And he completed the “100-man kumite,” fighting a hundred opponents in succession on three consecutive days.

None of these is documented in a way a historian would accept. The mountain training is known only from his own account and his organization’s. Bull demonstrations certainly took place, because one was filmed; but his own former students have said the filmed fight was staged, and much of the popular version comes from the manga Karate Baka Ichidai, which invented many episodes. Former students have also described the 100-man kumite as logistically impossible in the form usually told. We report all three as legend.

Building Kyokushin

The documented record begins in 1953, when Oyama opened his first dojo in Tokyo, first on an open lot and later in a former ballet school. His school became known for full-contact training at a time when most Japanese karate was taught without contact. In 1964 he incorporated the International Karate Organization Kyokushinkaikan and opened a world headquarters in Ikebukuro, Tokyo.

Growth came from a deliberate method. According to histories of Kyokushin, Oyama hand-picked instructors who could market the style and recruit members, as well as fight, and sent them to open branches abroad: Kenji Kurosaki in the Netherlands, Steve Arneil and Bob Boulton in Britain, Tadashi Nakamura and Shigeru Oyama in the United States, Mamoru Kaneko and Shigeo Kato in Australia, and others. Competition built the brand at home and abroad: the first All-Japan Open followed in 1969 and the first World Open Karate Championship in Tokyo in 1975. He also wrote prolifically, more than eighty books in Japanese, several of them published in English, and his books did for Kyokushin’s recruitment abroad what the tournaments did in Japan.

At its peak, the organization claimed more than 12 million members in between 100 and 123 countries, depending on the source. No independent audit of those figures exists, and they should be read as the organization’s own claim.

Death, and the succession

Oyama died of lung cancer in Tokyo on 26 April 1994. Shokei Matsui, then a relatively junior fifth-degree black belt, was named his successor on the strength of a will reportedly made a week before his death. Oyama’s family contested it, and the will was ruled invalid by the Japanese courts; sources differ on whether the decisive ruling came from the Tokyo Family Court in 1995 or from the Supreme Court in 1997.

The organization split almost immediately. Matsui led one faction; senior instructors led others; the family formed its own group; and further divisions followed, including the Kyokushin-kan founded in 2002 by Hatsuo Royama, who left saying the organization had been commercialized. Today Kyokushin is taught by at least half a dozen major international bodies, all claiming Oyama’s legacy.

What a school owner should take from Mas Oyama

Oyama’s expansion method is still the model for every multi-location martial arts brand: pick branch leaders who can sell as well as teach, give them the brand and the standards, and send them out to build. A great technician who cannot enroll students will not open a successful branch; Oyama understood that half a century before the phrase “franchise development.”

He also showed that a signature product builds a brand. Full-contact knockdown karate was a clear, visible difference from everyone else, and his tournaments and books put that difference in front of the public.

And his succession is the starkest warning in this archive. A founder who leaves his succession to a late, contested document risks everything he built. The larger the organization, the earlier the plan has to be written, witnessed and accepted by the people who will have to live with it.

Quick answers

Who was Mas Oyama?: Masutatsu “Mas” Oyama (1923–1994) was a Korean-born Japanese karate master who founded Kyokushin karate and built the International Karate Organization Kyokushinkaikan, one of the largest karate organizations in the world.
Did Mas Oyama really fight bulls?: He gave bull demonstrations, one of which was filmed, but his former students have said the filmed fight was staged, and many popular accounts come from a manga that invented episodes. The claimed count of 52 bulls is not documented.
Who succeeded Mas Oyama?: Shokei Matsui was named successor under a will that Oyama’s family contested and the Japanese courts later ruled invalid. The organization split into several rival Kyokushin groups.
When did Mas Oyama die?: He died of lung cancer in Tokyo on 26 April 1994, aged 70.

Sources, and what we could not confirm

Sources: the English Wikipedia biographies of Oyama, Kyokushin, Shokei Matsui and Hatsuo Royama and the sources they cite, for his early life, teachers, dojos, branch chiefs, tournaments, books, death and the split; the history published by a Kyokushin organization (labelled promotional) for the legends and membership claims; and a 2025 Japan-focused history blog, which carries no citations, for the date of the disputed will and the Supreme Court ruling.

Conflicts printed rather than smoothed over. His birth name is given as Choi Yeong-eui by most sources and Choi Yeong-seon by one. His birthplace is named as Gimje by one source; others say only Korea. The formal incorporation of the IKO is dated March 1964 by one source and April 1964 by another. The decisive court ruling on the will is dated 1995 (Tokyo Family Court) by one source and 1997 (Supreme Court) by another; they may be two stages of one case. Membership figures vary between sources and are the organization’s own.

Legends. The mountain training, the number of bulls and the 100-man kumite are reported as legend, for the reasons given above. Our sources differ on whether his Shotokan teacher was Gichin Funakoshi or his son; we have written “the Funakoshi family.” We have not been able to consult Japanese court records or contemporary Japanese newspapers.

Corrections. See our editorial policy. If you can add to or correct this record, we want to hear from you.