Around 1926, he began studying with Master Chotoku Kyan in the village of Katena. Shimabuku looked at Master Kyan as his first formal karate sensei, and developed and practiced the ki for which Kyan was known. Shimabuku had reached his full maturity of five feet two inches and about 120 pounds by this time in his life.

In the 1930s, Shimabuku studied with Choki Motobu as he continued to study with Sensei Kyan. With Motobu, he honed his skills in kumite (grappling).

Shimabuku was a farmer and karate teacher during the mid and late 1930s. During the occupation by the Japanese in the mid to late 30s, Shimabuku, being a businessman and an opportunist, invested all his money in horses and carts and was employed by the Japanese military to help build the air strips at Kadena, Okinawa. With the outbreak of World War II and the bombing and invasion of Okinawa by Allied Forces (U.S. Marines), Shimabuku's little business was destroyed. During this time he moved north into the mountainous terrain to escape from the heavily occupied southern territory held by the Japanese. Here in the north central part of Okinawa, Shimabuku and his family waited out the battle of Okinawa.

During the occupation of Okinawa by the Japanese, and prior to the invasion by Allied Forces, Shimabuku taught karate to the officers of the Japanese military. There were some pictures taken of Shimabuku and his Japanese students during this time, but most known pictures were destroyed by Shimabuku during the invasion by Allied Forces to keep his activities secret.

When the war was over, Shimabuku did not change his life style much; he kept farming as this was the only way to have enough food for his family. As more and more U.S. personnel were stationed on the island, Shimabuku quit farming and began teaching them "Chan MigwhaAe" (forerunner to lsshinryu Karate). The U.S. Special Services let contracts (about 1956) to many karate instructors on the island to teach karate to U.S. servicemen during their time off. Tatsuo Shimabuku was one of these instructors. He received about $250 a month. During the 'SOs this was a lot of money, especially to Okinawans who had struggled to exist during the war.

Shimabuku was recognized as being proficient in both Shorin-ryu and Goju-ryu. Master Shimabuku was never a dan in either style because there was no such thing at the time. In those days there was no formal ranking system, as such, one was judged as a black belt or a master based on one's actions as viewed by one's fellow karate-ka.

After Sensei Kyan's death on September 20,1945, Shimabuku began studying with Master Chojun Miyagi where he furthered his ki and learned Goju-Ryu katas. He studied with Miyagi until Miyagi's death on October 8, 1953. It was during this time that Shimabuku began experimenting with new techniques. He wanted to change the techniques to be quicker and faster. He used kendo protective equipment during kumite. This is when he started developing different ways to block and punch. Shimabuku went on to further his study of weapons with Tirara Shinkenin the 1950s and 1960s.

On January 14,1954, Tatsuo Shimabuku went to sleep and had a dream. In this dream he saw a vision of a goddess, half woman and half sea serpent. One of her hands was raised in a fist, and the other was lowered and open. A dragon was flying in the gray sky above.

When Master Shimabuku awoke the next morning, he believed that the dream was divinely inspired. It was on this day, January 15,1954, (refer to Master Tatsuo Shimabuku's letter dated February 26,1959 included herein and signed by the late Master) that he decided to break away from Okinawan traditional styles. He was to name this new style of Karate - lsshinryu.

This dream goes back to Master Shimabuku's teaching in Taoism and his changing his given name from Shinkichi to Tatsuo. Tatsuo means dragon in Japanese. But the most important thing in Tao teaching is that the dragon symbolizes supreme wisdom, power, control, and social influence. Now, going one step further, the "Flying Dragon" in Master Shimabuku's dream always depicts rain, wind, clouds, and lightning.

Before this day, Master Shimabuku had been developing and refining his ideas. He called what he taught before lsshinryu, "Chan Migwha-Te." This name was in honor of Master Kyan. Kyan's nickname was "Migwha" meaning "small eyed chan" (Chan is the Okinawan pronunciation for Kyan) and "Te" means hand. So this school was the "small eyed Kyan's Karate."

After telling his senior students of his decision to break away from Okinawan traditional styles, many of his students left him. Master Shimabuku continued with his decision to formulate a new style that was radically different from other Okinawan karate styles and began looking for a name for his new system. In 1954, one of Master Shimabuku's senior students, Eiko Kaneshi, suggested the new name. In the original kanji (characters), the name was "lsshindo". In 1956, Master Shimabuku changed the kanji to read "lsshinryu"; as it is today.

On February 26,1959, Master Shimabuku held an exhibition party for the third anniversary of Karate lsshinryu modes as shown by the document written by Master Shimabuku in his own hand. During the early years of lsshinryu karate, 1956-57, Masters Harold Long and Don Nagle studied lsshinryu from Master Shimabuku. Thus, at this time in Grand Master Shimabuku's life, lsshinryu and Shimabuku became one.

Master Shimabuku always had a number one Okinawan student and a number one American student. Eiko Kaneshi was the number one Okinawan student. Kinjo Kinsoku was his best Okinawan student, and Sensei Harold Mitchum became his number one and best American student, but before Mitchum became Shimabuku's number one student, there was a Marine by the name of Sergeant Hall, an EA. All that Sensei Mitchum remembers of him was that "he sure hit hard." After Hall left Okinawa, Sensei became the Master's number one and he never had an equal. Hall is the man who took Mitchum to meet Master Shimabuku and on March 23,1958, Sensei Mitchum officially started studying lsshinryu Karate.

In 1959, Master Tatsuo Shimabuku's classes had grown so large he opened another school down the street about two blocks from the main dojo in Agena village. (Agena is a suburb of Gushikawa City.) At the second dojo Master Shimabuku had Sensei Mitchum teach; Sensei Mitchum taught Americans and Okinawans alike. The Master had a small area at one end of this dojo where his daughter and son-in-law, Yukis and Angi Uezu lived. Angi Uezu did not start studying lsshinryu until the mid '60s. Master Shimabuku opened another dojo across the street from the gates of Camp Hanser.

In the early '60s, the Special Services cancelled the Martial Arts contracts with local instructors. Master Shimabuku did not understand why. So he asked Mitchum to go with him to find out why he lost the contract teaching karate to U.S. based personnel. It was explained to the Master and Mitchum by the Special Services officer that Special Services thought that they were paying too much for the services. They (Shimabuku and Mitchum) were told that Special Services were going to conduct a study to find out what an instructor in Japan was paid and adjust the contract pay according to the study. Master Shimabuku, along with other instructors, got their contracts renewed at about the same old rate.

In 1960, a meeting/party was held in Agena, Okinawa to establish an Association. Master Tatsuo Shimabuku, Kinjo Kinsoku, Eiko Kaneshi, Harold Mitchum, Steve Armstrong, an interpreter, and others were present. There were two main decisions that came from this meeting: 1) the Okinawan- American Karate Association was established, and 2) Harold Mitchum was installed as the President of the newly formed Association. The Association established dues to be paid every month and the membership roster of members was made up by Ralph J. Bove and Harold Mitchum (See list of membership in Association in 1960). The only names of Americans not listed are Harold Mitchum, Steve Armstrong, Ralph J. Bove, who were officers in the Association.

In 1961, the Association's name was changed from Okinawan-American Karate Association to American-Okinawan Karate Association and a newsletter was sent out stating that all Dan grades awarded prior to June 10,1961, were invalid. All black belts went back to Sho-Dan Grade and Master Shimabuku reissued other ranks accordingly. Also a formal letter was issued by Grand Master Shimabuku appointing Mr. Harold M. Mitchum to the post of A.O.K.A. President.

About 1963 the main dojo had a roof put on using A.O.K.A. funds. Also, there were pictures in the local newspaper of Master Shimabuku donating money to a local charity.

In 1966 Master Tatsuo Shimabuku visited the United States. Mr. Steve Armstrong had Master Shimabuku flown to Tacoma, Washington, from Okinawa to visit with him. From there, he was flown to Knoxville, Tennessee to Mr. Harold Long's dojo. From Tennessee, he flew to New Jersey to see Mr. Don Nagle and from there he returned to Mr. Steve Armstrong's dojo in Tacoma, Washington. During this time all three were promoted to eighth Dans. Mr. Steve Armstrong filmed Master Shimabuku doing the 14 lsshinryu katas; 8 empty hand and 6 weapons katas.

Master Shimabuku turned over the running of the Association to Kichiro in the early 1970s.

On May 30,1975, Master Tatsuo Shimabuku died. After cremation, the Master was buried in a beautiful Botanical Garden Cemetery close to Kadena Air Base, along side his oldest daughter. Master Tatsuo Shimabuku's wife lives with the youngest son at this time.

Grand Master Tatsuo Shimabuku first intended to give the lsshinryu System to his number one student but to appease his angry son, on his deathbed Grand Master Shimabuku gave lsshinryu Karate on Okinawa to Kichiro. The Grand Master had given directions to his lsshinryu leaders in America to teach lsshinryu Karate and expand their organizations. These leaders were Harold Long, Steve Armstrong, Harold Mitchum and Don Nagle. Master Kichiro Shimabuku began the lsshinryu World Karate Association, with a branch in the United States. The American Okinawan Karate Association remained active with Master Armstrong at the helm. 

Chotoku Kyan	Miyagi Chojun	Choki Motobu	Taira Shinken