Legend of the Dragon Kings

"Legend of the Dragon Kings" (known as "Souryuuden" in Japan) is a fantasy and supernatural anime series based on the Japanese novel series of the same name. The story revolves around the four Ryudo brothers who are believed to be descendants of the ancient "Dragon Kings." They lead seemingly normal lives until their destinies are awakened by mysterious happenings. Hajime, the oldest brother, discovers that he has the power to transform into a dragon. The other three brothers, Tsuzuku, Owaru, and Amaru, soon discover that they also have the ability to turn into different types of dragons.