The 'Azure Dragon' - 'Qing Long' (or 'Seiryuu' in Japanese) is one of the Four Symbols of the Chinese constellations and also one of the four guardian spirits of Japanese cities.
Each one of them represents a direction and a season of the year, and each has its own individual characteristics and origins. They have been portrayed in many historical Chinese myths and fiction, and also appear in many modern Japanese comic books and animation.
These Four Symbols were given human names after Daoism became popular.
Azure Dragon has the name Meng Zhang; Vermilion Bird is Ling Guang; White Tiger is Jian Bing; Black Tortoise is Zhi Ming. Additionally, there is a fifth legendary beast, Huang-long, or the Yellow Dragon of the Center.
The cardinal direction associated with this animal is "centre," and its element is Earth. It is sometimes called the Azure Dragon of the East (pinyin: Dong Fang Qing Long), and it represents the east and the spring season.
It should not be confused with the mythological yellow dragon that is associated with the Emperor of China.