When a student of karate hears the term “Shotokan Tiger,” one image comes to mind: the traditional symbol of the tiger inside the circle which has become representative of Shotokan Karate.
That symbol is properly called the “Tora no Maki,” or the Tiger Scroll.
The drawing was originally created by a Japanese man named Hoan Kusugi who was a friend and student of Funakoshi. The character up in the northeast quadrant of the circle is part of the artist’s signature.
Kusugi was reportedly instrumental in convincing Funakoshi to teach karate in Japan. He also was the man who first convinced Funakoshi to write his knowledge of karate into a book, and promised him that if he would, he would design the book and make a drawing specifically to illustrate the book cover.
“Ryukyu Karate Kenpo,” Funakoshi’s first book about karate, was written in 1922, but the plates for that original book were destroyed in the fire of the Great Kanto Earthquake in September of 1923. Later that year, Funkoshi released the book again, this time under the name of “Rentan Goshin Jutsu.”
Kusugi is reported to have declared to Funakoshi that his book was the master text of karate. In Japanese, the master text for a particular topic is called the “Tora no Maki,” recalling the traditional practice of writing their documents as long scrolls. Already by Funokoshi’s time, the practice had been long abandoned, but the name stuck.
“Scroll of the Tiger” in this case is idiomatic and means “Key” or “Book of Knowledge.” The picture of the tiger in the circle is a pun on the words “Tora no Maki,” which could also be taken to mean “Roll of the Tiger.”
When Funakoshi created our system of martial arts, he chose the tiger as the animal symbol to represent Shotokan because it signified strength, power, and tenacity.
The tiger in the traditional circular image is a traditional Chinese design that implies “the tiger never sleeps.” It symbolizes, therefore, the keen alertness of the wakeful tiger and serenity of the peaceful mind.
The Shotokan Tiger is drawn within a circle to show that the power of the tiger, like the power of Shotokan, is contained. It indicates that this power should never be used on a whim. The power is only unleashed, or broken from the circle, in order to defend ourselves or others who can’t defend themselves from a violent attack
Source: http://www.shotokanhouston.com/resources/shotokan-tiger-symbol/