Soryuden: Volume 4

Once the dark masters had laid their eyes upon the superhuman powers of the dragon brothers, they decideded to kill the eldest brother Hajime at soon as possible. Tsuzuku can release damaging fire, Owaru can call upon the wind, and even Amaru can cause the rain to pour without stopping. Therefore, the time for Hajime changing himself into a dragon must soon be at hand. The world-dominating Four Sisters is concealing an evil imperial scandal which will induce the final battle of humankind!

According to Tanaka's version of the dragon king stories, the four Gou's brothers--Gou Kou, Gou Shyo, Gou Jyun and Gou En ("Gou" being their family name)--faught the war against the tyrrant of the Yin Dynasty (1066 BC). In those days, there are half-human monsters, and the Bull's clan was the greatest enemies of the Gou's family.