Masutatsu Oyama was born in July 12, 1923 in Qa-Ryong-Ri Yong-chi-Myo'n Chul Na Do, near the town Kinje not far from Gunsan in the south-west of Korea. The village is close to the Yellow sea which for centuries was occupied by Chinese and Japanese pirates. Who were known for there ravaging along the coastline. His child given name was Hyung Yee Choi, but when he immigrated to Japan, they pressured him to take a Japanese name. He chose Oyama which means "great mountain", in honor of the family that befriended him and took him in, while in Japan.
Young Hyung Yee was one of the lucky few in the province of Cholapuk Do, belonging to the Yangban-clan his family was aristocratic. The father, Sun Hyang like Hyung Yee and his three brothers were all unusually powerfully built. The family who was quite wealthy had a large country-estate and his father was also the mayor of Kinje. The road to Yongee Primary School was dirty and narrow and Hyung Yee had to like the other children walk the ten kilometres to school. His class containing 60 pupils in a school with a total of 400 pupils.
At a relatively young age he was sent to Manchuria, in Southern China, to live on his sister's farm. At the age of nine, he started studying the Southern Chinese form of Kempo called Eighteen Techniques (Shaku-riki system) his teacher was Mr. Yi who was at the time working on his sister's farm. Mas Oyama studied with Mr. Yi for about 2 years He attained the level equivalent to Shodan.
At the age of 13 he returned to Korea to live with his aunt in Seoul and to attend Junior High School. Hyung Yee was not really interested in his schoolwork. He enjoyed more being outdoors, fishing and swimming with his friends. The one thing that interested him the most was athletics. He participated in football as well as cross-country running. Even though he failed to show any kind of interest when his brothers tried to teach him boxing, he preferred a Martial Art named Taiken or Chabee. He was very devoted and rarely missed a training opportunity. 
Taiken or Chabee, a Korean arts were a mixture of Kempo, which was similar to Kung Fu, and Ju Jitsu. Chabee came from the Koryo-period (912-1392). Before the Koryo-period, the Korean peninsula was unionized by the royalty Silla. The fighting techniques used at the end of the Silla-era was a mixture of Chinese and Korean martial arts, favored on Chinese hand techniques. It was very different from the old Korean martial arts which had contained a lot of head-, elbow- and foot-techniques. During the koryo-era the Korean peninsula blossomed, materially, as well as culturally. It was also during this time the so called eighteen-techniques developed.
Later a system named the thirty-six-techniques was developed and finally both these systems became Chabee.This training continued until about the age of 15 years. At this point he was moved to Tokyo, Japan to train as an aviator, to be like Bismarck, his hero of the time. He was enrolled at the Yamanashi Youth Aviation Institute. Survival on his own at that age proved to be more difficult than he thought, especially as a Korean in Japan, and the aviator training fell by the wayside. During this time he started training in boxing and Judo. One day he noticed some student training in Okinawa karate, he got interested and went to train at the Dojo of Gichin Funakoshi at Takushoku University, where he learned what is today known Shotokan Karate. His training progress was very impressive, by the age of seventeen he was already a 2nd Dan, by the age of 20, he was a 4th Dan. At this point he also took a serious interest in judo, and his progress there was no less amazing. By the time he had quit training in Judo, less than four years after he had started, he had achieved the rank of fourth Dan in Judo.

At this time Mas Oyama entered the Butokukai which was the trained academy for the imperial Japanese Military. The Butokakai specialized in guerrilla warfare, espionage, and hand to hand combat. Sosai spent 2 years in this organization which ended with the close of World War II. The defeat of Japan and the subsequent indignity of Occupation was very hard to take by Mas Oyama. At this time he decided to continue his training under the direction of Master So Nei Chu, also a Korean (from Oyama's own province) living in Japan was a Goju expert and student of Chojun Miyagi, the founder of Goju Karate. So Nei Chu renowned for his physical and spiritual strength, was purported to be the leading expert of Goju Karate in Japan at the time, next to Miyagi Sensei. It was Master So who encouraged Sosai Oyama to undertake his mountain retreat to strengthen his technical skills and temper his spirit. He was accompanied by one of his own students, but after six months of isolation, the student secretly fled during the night leaving Mas Oyama to continue his vigorous training alone which became even harder for Oyama, who wanted more than ever to return to civilization. So Nei Chu wrote to him that he should shave off an eyebrow in order to get rid of the urge. Surely he wouldn't want anyone to see him that way! This and other more moving words convinced Oyama to continue, and he resolved to become the most powerful karate man in Japan. Soon however, his sponsor informed him that he was no longer able to support him and so after 14 months, he had to end his solitude. A few months later in 1947, after returning to civilization, he tested his abilities in the Karate division of the first Japanese National Martial Arts Championships, which he won. However, he felt empty for not having complete the 3 years of solitude. He then decided to dedicate his life completely to karate-do, so he started again this time on mount Kiyozumi also in Chiba Prefecture. He chose this site for its spiritual uplifting environment.

This time his training was fanatical - 12 hours a day every day with no rest days, standing under (cold) buffeting waterfalls, breaking river stones with his hands, using trees as Makiwara, jumping over rapidly growing flax plants hundreds of times each day. Each day also included a period of study of the ancients classics on the Martial arts Zen, and philosophy.

After eighteen months he came down fully confident of himself, and able to take control of his life. Never again would he be so heavily influenced by his society around him. (Though it is probably safe to say that his circumstances were also probably never again as traumatic!)

In 1950, Sosai (the founder) Mas Oyama started testing (and demonstrating) his power by fighting bulls. In all, he fought 52 bulls, three of which were killed instantly, and 49 had their horns taken off with knife hand blows. That it is not to say that it was all that easy for him. Oyama was fond of remembering that his first attempt just resulted in an angry bull. In 1957, at the age of 34, he was nearly killed in Mexico when a bull got some of his own back and gored him. Oyama somehow managed to pull the bull off and break off his horn. He was bedridden for 6 months while he recovered from the usually fatal wound. Today of course, the animal rights groups would have something to say about these demonstrations, despite the fact that the animals were already all destined for slaughter. In 1952, he traveled the United States for a year, demonstrating his Karate, live and on national television. During subsequent years, he took on all challengers, resulting in fights with 270 different people. The vast majority of these were defeated with one punch! A fight never lasted more than three minutes, and most rarely lasted more than a few seconds. His fighting principle was simple — if he got through to you, that was it. If he hit you, you broke. If you blocked a rib punch, you arm was broken or dislocated. If you didn't block, your rib was broken. He became known as the Godhand, a living manifestation of the Japanese warriors' maxim Ichi geki, Hissatsu or "One strike, certain death". To him, this was the true aim of technique in Karate. The fancy footwork and intricate techniques were secondary (though he was also known for the power of his head kicks). It was during one of his visits to the United States that Sosai Masutatsu Oyama met Jacques Sandulescu, a big (190 cm and 190 kg of muscle) Romanian who later on become very well know in Kyokushin. They quickly became friends and remained so for the rest of Sosai Oyama's life, and Shihan Jacques still trains and acts as advisor to the IKO(1) to this day. In 1953, Sosai Masutatsu Oyama opened his first "Dojo", a grass lot in Mejiro in Tokyo. In 1956, the first real Dojo was opened in a former ballet studio behind Rikkyo University, 500 meters from the location of the current Japanese Honbu Dojo (headquarters). By 1957 there were 700 members, despite the high drop-out rate due to the hardness of training. Practitioners of other styles came to train here too, for the jis-sen Kumite (full contact fighting). One of the original instructors, Kenji Kato, has said that they would observe those from other styles, and adopt any techniques that "would be good in a real fight". This was how Sosai Masutatsu Oyama's Karate evolved. He took techniques from all martial arts, and did not restrict himself to Karate alone. The students of Sosai Masutatsu Oyama took their Kumite seriously, because this was a full contact style, so they expected to hit and to be hit. With few restrictions, attacking the head was common, usually with the palm heel or towel-wrapped knuckles. Grabs, throws, and groin attacks were also common. Kumite rounds would continue till one person loudly conceded defeat. Injuries occurred on a daily basis and the drop out rate was high (over 90%). They had no official do-gi and wore whatever they had.

In 1952, Sosai Masutatsu Oyama gave a demonstration in Hawaii. A young Bobby Lowe saw him and was stunned by the power of Sosai Masutatsu Oyama demonstrated. It was not as though Bobby Lowe was inexperienced in martial arts. Though still quite young, his achievements to date were not much less than those of Sosai Masutatsu Oyama himself. His father had been a Kung Fu instructor, and he had participated in any fighting art he could find. By the age of 23, he was Yondan in judo, Nidan in Kempo, Shodan in Aikido, and a highly regarded welterweight boxer. It was not long before Bobby Lowe became the first Kyokushin uchi deshi or "live-in student" of Sosai Masutatsu Oyama. He trained daily with Sosai Masutatsu Oyama for one and a half years. Eventually, an uchi deshi's time became "1000 days for the beginning". These uchi deshi became known as Wakajishi, or the "Young Lions" of Mas Oyama and only a few of the hundreds of applicants were chosen each year for the privilege of training full time under the Master. In 1957, Shihan Bobby Lowe returned to Hawaii to open the first School of Oyama outside Japan.

The beginning of Kyokushin: The current World Headquarters were officially opened in June 1964, where the name Kyokushin, meaning "Ultimate truth" was adopted. From then, Kyokushin continued to spread to more than 120 countries, and registered members exceed 10 million making it one of the largest martial arts organizations in the world. Among the better known Kyokushin Yudansha (black belts) are Sean Connery (Honorary Shodan), Dolph Lundgren (Sandan, and former Australian heavyweight champion. Famous movie star). Also some adepts claim that Nelson Mandela, the President of South Africa, has an honorary 8th Dan, given by the Kyokushin Organization on June 01, 1995. However they fail to mention that Nelson Mandela never accept this Belt, many believe that the reason for this is because Kyokushin in South Africa support the Apartheid Regime.
  Sadly, Sosai Masutatsu Oyama died of lung cancer (as a non-smoker), at the age of 70 in April 1994, leaving a confuse organization which split into three mayor groups. The IKO1, under the leadership of Shihan Akiyoshi Matsui, the IKO2, under the leadership of Shihan Yukio Nishida, and the IKO3, under the leadership of Shihan Yoshikazu Matsushima. Those three groups have the difficult task of maintain the spirit and the teaching of Kyokushin alive. This has had many political and economic ramifications throughout the Kyokushin world, which are still being resolved. In the end, the result may well be a splintering of Kyokushin, much like Shotokan now appears to have done, with each group claiming to be the one-and-only true heir of Mas Oyama's Kyokushin, either spiritually or even financially. It is however reasonably certain that all Kyokushin groups, regardless of their ultimate allegiance, will still maintain the standards set by Sosai Masutatsu Oyama. Maybe a Kyokushin disperse will be a good thing, since in all good families, some of the children eventually do leave home and start their own families. Some of the splinter groups may remain faithful to the Kyokushin principles, such as Hanshi Steve Arneil in Great Britain did in 1991. Many others, such as Shigeru Oyama in the U.S., have taken it further by developing their own style based on Kyokushin