Gogen Yamaguchi (A.K.A “The Cat”) one of ten children was born on January 20, 1909 in the city of Kagoshima, which is located on the southern end of Kyushu Japan. He was named Yoshimi Yamaguchi by his father, Tokutaro, who was a merchant, a school teacher and superintendent. His mother, Yoshimatsu, was Tokutaro's assistant. As a boy Yamaguchi trained in the art of Jigen-ryu Kenjutsu (kendo). As a young teen, when his family moved to Kyoto, Yamaguchi began studying Goju-ryu in the Maruta Dojo in Miyazai, Kyushu under Takeo Maruta, a carpenter by trade.

In 1929 Yamaguchi entered Ritsumeikan University in Kyoto and majored in Law. In 1930 he started the first karate club on the Ritsumeikan campus. It was not long before the hard training and distinctive breathing exercises (ibuki) made the club well known throughout the city. It was during this time that Yamaguchi began work on jiyu kumite, which translates as free fighting or sparring. Masters and teachers of this time stressed kata and were not very big on free sparring as techniques were done in full force and without control. The system Yamaguchi developed was based on the sparring system of kendo where points are scored for striking specific targets, and eventually would become the basis for modern day tournament fighting.

In 1931 Yamaguchi, age 22, was introduced to Chojun Miyagi, the founder of Goju. Up to this point in his training Yamaguchi had focused on the "hard" aspect of Goju. Yamaguchi was so well trained in the hard side of Goju that Miyagi gave him the name "Gogen" meaning "rough". After meeting Miyagi he became aware of his need to train his "soft" spiritual side as well. Yamaguchi immediately fell in love with the strange and intricate patterns displayed by Miyagi. From that moment on, the future of Yamaguchi was sealed. He concentrated on the study of Goju to the exclusion of almost everything else. When Miyagi left to return to Okinawa, he left behind a well-trained and dedicated follower. Miyagi later named Yamaguchi the leader of Goju Ryu on mainland Japan.

Yamaguchi Sensei was later dubbed “The Cat” by a group of America GI’s during his post war years teaching allied troops karate in Japan. There are several theories as to why they nicknamed him “The Cat”. There are those who say it was because of his long flowing hair resembling a lion's mane. Others say it is due to his preference for the cat stance in Goju as well as his cat-like gaze he would often lock his opponents with. Others say the name came from his legendary battle with a tiger during his time as a POW.

Yamaguchi Sensei added the Taikyoku kata’s to the Goju system, which are used as an introduction for beginners to help prepare them for the more advanced kata’s of the goju – ryu system. Yamaguchi Sensei also designed and sketched the now famous Goju-ryu fist insignia, modeled after the right fist of Chojun Miyagi.

In 1934 Yamaguchi graduated from Ritsumeikan University, and also introduced Jiyu-Kumite after completing his development of the rules for free fighting that is known today as tournament fighting kumite. That next year in 1935 he started the All Japan Goju-kai Karate-do Association that later (in 1955) became the International Karate-do Goju-kai Association – IKGA. Also in 1935 Yamaguchi Sensei began his travels with the Japanese government as an intelligence officer and his first son Norimi Gōsei Yamaguchi was born.

In 1938 General Ishihara requested Yamaguchi Sensei to take a Governmental post in Manchuria, which had been renamed the Republic of Manchu-kuo. During his tour of duty in Manchuria, from 1938-1945, Yamaguchi was captured by the Soviet military in 1942 and incarcerated as a prisoner of war in a Russian concentration camp. Legend has it that the Russians having tried and failed at breaking Yamaguchi Sensei then thought of a novel way to just get rid of him. His Russian captors captured a hungry tiger and decided to throw Yamaguchi into the same cage. The show they got was not one they expected. Instead of being torn apart Yamaguchi kicked the tiger in the nose and elbowed it in the head. He then leapt on the big cat's back, applied a strangle hold and choked it to death. His Russian captors, perplexed at what just happened questioned who he was and when they found out, they had him teach them karate.

In 1947 after two years as a Russian prisoner Yamaguchi returned to Japan. Upon his return Yamaguchi was shocked and heart broken at the condition of Japan after World War II both physically and spiritually. During the war many Goju schools had closed. Only a few had remained open with no real leadership. On the verge of suicide himself, due to the state of his country and his art form, Yamaguchi experienced a revelation that discovered his own purpose in life. He was to teach and spread the martial arts to the youth of his nation. To aid in his goal of spreading martial arts Yamaguchi held a week long exhibition in Tokyo. This exhibition showcased the various traditional Japanese arts as well as various Chinese arts he learned while in China. Slowly, Yamaguchi began reconsolidating the Goju schools that had remained open through the war, while constantly opening new ones.

Following the war, Yamaguchi Sensei was focused on the spread of martial arts and to better himself physically, mentally and spiritually. He sought out Reverend Tadaki Yoshimura, Chief Reverend of Shin-shu Shinto, and eventually became a Shinto master as well. Yamaguchi also learned yoga from Tengai Noda, Japan's leading expert and yoga master at the time. Eventually Yamaguchi would meld these together with his Goju to form his personal system of Goju Shinto.

The face of Goju ryu and martial arts in general would be amazingly different if not for the influence of Gogen Yamaguchi. Primarily due to his efforts Goju-ryu was formally registered and recognized by the Butoku-kai, the governing body for Japanese martial arts. This is the same organization that awarded Yamaguchi the title of Renshi (senior expert/5th dan) in 1940. In 1950 he founded the Zen Nippon (All Japan) Karate-do Goju-kai, a national organization in Japan. In 1951 Yamaguchi took enough time for himself to get his Judan (10th black belt) from Chojun Miyagi. All the karate dojos in Japan were united in 1964 under the Federation of All Japan Karate-do Organization (FAJKO), which is today known as the Japan Karate Federation (JKF). While accomplishing all of this Yamaguchi was appointed as Shihan (master) of the karate division of the Kokusai Budo Renmei, the International Martial Arts Federation in Japan. This appointment came from the federation chairman, Prince Higashikuni of the Japanese Imperial Family. Another noteworthy Imperial contact occurred in 1968 when Emperor Hirohito presented Yamaguchi with the Ranju-Hosho (Blue Ribbon Medal) for his contribution to the martial arts.

Even in his late 60's Yamaguchi showed no signs of slowing in his mission to spread the martial arts. He founded and opened the Japan Karate-do College in Suginami, a suburb of Tokyo, Japan. This school served as Yamaguchi's home as well as the Goju-kai headquarters. In order to give students of the college a well rounded martial arts education, the ground floor dojo level of the building taught classes in Goju and other styles. The second floor was a yoga-shinto center for the education and practice of those two arts. The top floor served as a dormitory with accommodations for about 12 students.

Gōgen Yamaguchi visited Sydney and Melbourne on two occasions, in 1970 and 1972. He was the first Grandmaster to ever visit Australia. Yamaguchi Sensei died on the 20th of May 1989. He had been married twice, firstly to Midori (who still lives on the island of Kyushu), with whom he had four children: Gōsei Norimi Yamaguchi, Gōsen Kishio Yamaguchi, Makiko Yamaguchi, and Gōshi Hirofumi Yamaguchi. He and his second wife, Mitsue, had one child, Gōkyōko Wakako Yamaguchi. All of his children practiced karate-dō and became Masters in their own right. The names commencing with gō (剛) were their karate names. Gōsei Norimi Yamaguchi has his own organisation in the United States and Gōshi Hirofumi Yamaguchi is the President of the International Karate-dō Gōjū-kai, with branches in 60 countries. Gōsen Kishio Yamaguchi was the Vice President of Japan Airlines. Kishio, who died in the early 1990s, was deeply involved in the running of the I.K.G.A whilst his youngest sister Wakako Yamaguchi was an All Japan Kata Champion for a number of years. Makiko Yamaguchi died from cancer at a relatively young age during the early 1980s.