The three stars, not circles
Three stars are a symbol of victory. Three stars are also used to represent the Orion constellation. There are also link to three generals. however I ecpext Jason to chip in some info from Murray himself.
Mitsuboshi means:
Mitsu = Three
Boshi = Star
You might find some info here:
http://www.otomiya.com/kamon/sizen/hoshi.htm
Ancient Japanese Astronomy and Mythology
Stars that played a significant role in the lives of common citizens in Japan were often given the distinction of being called Yowatashi Boshi or passing the night stars. This phrase was applied to prominent star groups which would appear in the East at sunset and set with the dawning sun. Orion is certainly one of the most noticeable Yowatashi Boshi in the sky.
In most every culture, it is easily recognized and continues to grab the attention of children and adults throughout the long winter nights. The grouping of stars that form the constellation, most especially the three belt stars or Mitsu Boshi have played a major role in Japan's cultural heritage with the sky.
As one of many groups of stars with which Japanese formed associations, Orion is a particularly rich "case study" in the ways in which Japanese historically made the sky a part of their lives. In the case of Orion, Japanese have seen few if any individual gods or heroes or even mythological creatures within the constellation as a whole but rather icons of common knowledge or use and symbols of specific cultural values and attributes.
While some star lore reflects a kind of national "consciousness", there is no singular Japanese interpretation of the star patterns but rather a variety of objects, memorialized events, seasonal markers, symbols of religious value, and legends based on particular geographical regions and functional needs of ordinary citizens
Link:
http://www.crystalinks.com/japanastronomy.html
Heres a thread from another forum
http://www.kendo-world.com/forum/archive/index.php/t-3930.html