This symbol is ubiquitous on Buddhist and Shinto temples all over Japan. Its name is tomoe, meaning turning or circular, referring to the motion of the earth. The tomoe is related to the yin yang symbol, and has a similar meaning, representing the play of forces in the cosmos. Visually, the tomoe is made up of interlocked flames resembling tadpoles.
The Futatsu Tomoe has been used by various Warrior families, sects and clans throughout the history of China and Japan. As a matter of fact, it is the family crest of one of my MeiBuKan GoJu Ryu Sensei’s “ Ikemiyagi “ who I spent time with while I was living in Okinawa. Ikemiyagi’s family originally came from China.
During a recent epiphany of mine, I realized that our use of it is symbolic of the cycle of perpetuation of both the positive and negative teachings that we experienced from our own teachers and parents, and thereby pass on later to our students and children. This reminder of such perpetuation serves as a tool as for us to attempt to be cognizant of what we carry with us as negative vs. positive, understanding that a balance of the two is extant, but not necessary to pass on.
Of course the duality of this symbol represents the Hard and soft = Go Ju
It can also be seen in concept used in various technique, such as this one being executed by yours truly, called Tomoe Nage.