According to Chinese mythology, there were originally ten sun crows which settled in ten separate suns. Each day one of the sun crows would be rostered to travel around the world on a carriage driven by Xihe, the "mother" of the suns. As soon as one sun crow returned, another one would set forth in its journey crossing the sky. One day all ten sun crows came out on the same day, causing the world to burn; the celestial archer Houyi saved the day by shooting down all but one of the birds.
"A three-legged bird said to live in the sun. In ancient China, there used to be 10 suns which would take turns traveling the sky. But one day, all ten suns appeared in the sky and scored the earth. A man named Hou Yi shot down nine of the suns."
"Ancient Chinese legend has it that once there were ten suns that strode across the sky, each in succession. One day, all ten appeared at once, bringing flame to sear sky and earth alike. A hero named Hou Yi raised his bow to shoot down nine of the suns, sparing humanity and the earth. It was said that a three-legged Kau lived within each of the suns. Now, only one travels across the sky, bringing light to the world. It's sic fires burn strong enough to warm, but not to sear and scar."
—Devil Survivor 2 compendium
Part of Special Fusion Pack Vol. 1, Kau is a special fusion of Kama and Tonatiuh.