The inspiration for this symbol comes from one of the old texts of Kitoryu Jujitsu called Ten no Maki (Scroll of Heaven). This text explains that the characters meaning rise and fall represent the opposites active and passive respectively. Being active can lead to victory but so can being passive by weakness overcoming strength.
The character meaning rise signifies the power of fire, the character meaning fall signifies the power of water. The sun is a source of energy and water has no form or thought but simply adapts to its environment. However, water has the power to outrival everything, to nourish all things yet remain humble. These are the strengths of the most virtuous people and it is said that virtue is the same as water in this sense.
This symbol is composed of red representing fire, blue representing water and white representing infinite space.