Blue friends. The letter P comes from the cartoon Rainbow Friends. By understanding the animated story, we can know that the letter P is a friend of blue, which is the blue in Ayabeni color. Rainbow, also known as Tiangong (Hakka), rainbow over the sky, crimson and so on. , is an optical phenomenon in meteorology. When sunlight hits the water droplets in mid-air, the light is refracted and reflected, forming an arched colorful spectrum in the sky. From the outer ring to the inner ring, there are seven colors: red, orange, yellow, green, blue, indigo and purple.