Isshinryu is a Traditional Karate system developed in Okinawa by the great master Soke Tatsuo Shimabuku, who after having mastered Goju Ryu and Shorin Ryu, decides to take the elements that he considers best and most effective of both styles, to synthesize them in the Isshinryu. Incorporating the Kobudo or combat with weapons, from the prestigious line of Master Shinken Taira.

Soke Tatsuo Shimabuku thus developed a combat system with fast, powerful and direct kicks and blows, devoid of superfluous movements; replacing the punch where the wrist rotates before landing the punch, by the trademark of the Isshinryu, the punch with the vertical fist or Tate Ken Tsuki.

Tate Ken is based on the natural movements of a real fight, where horizontal punches are replaced by vertical punches because they are faster and more effective. When this technique was carried out, the hand was turned halfway, so time was lost as well as forced to open the elbows. In addition, the traditional blow was weak and left a situation of risk before a Jujitsu or Judo practitioner when offering the arm, therefore Master Tatsuo modified the blow, doing it vertically, preserving the principles of relaxed body and tight pectoral and dorsal. The blow stretched the arm to 87% returning to quickly protect the rib area.

On the other hand, Master Tatsuo saw that in the block of his students, the arms usually had bruises or even broke, since it was a very rigid system. He came to the conclusion that he should modify it and use the muscles of the arm and not the bones as he had been doing.

Tatsuo Shimabuku had his modifications endorsed and approved by the masters council. His intention was not to spread a tool of violence, but rather a source for the personal development of:

 

Mental, physical and spiritual strength

Self discipline

Self-confidence

Ability to protect yourself

Ability to protect the family

 

Many of the US Marines, who trained under Grandmaster Tatsuo Shimabuku, brought the Isshinryu to the United States; This contributed to its popularity and growth.

In 1960 the first international Isshinryu association was founded, initially it was called the Okinawan American Isshinryu Association (OAKA), later it was renamed the American Okinawan Karate Association (AOKA). The founders of this association were the teacher Tatsuo Shimabuku, Harold Mitchum, Kinjo Chinsaku, Ralph Bove, William Blond and Steve Armstrong; later Don Nagle and Harold Long joined.

Tatsuo Shimabuku visited the United States twice, in 1964 and 1966; on his last visit he was filmed performing Isshinryu's kata. On this visit he promoted Steve Armstrong, Don Nagle and Harold Long to eighth dan; Harold Mitchum had previously obtained this degree.

It was only on January 15, 1956, when he called his students to tell them that he would call the Isshinryu style. Isshinryu means the method of a mind or the method of a heart. Sensei Eiko Kaneshi, Grandmaster Tatsuo's right arm, indicates that he gave it that name because all things begin with only one. Sensei Arsenio Advíncula interviews him in 1969 and asks him if there is an anniversary for the birth of the Isshinryu; He replies that something like this doesn't exist, because it didn't take a single day to create the system, and that he continues to experience things through the years.

Since the great master Tatsuo Shimabuku did not set a date to commemorate the birth of the style, it is considered that the date of birth of master Tatsuo, is on which we should commemorate this event.