Soryuden Novel Volume 01 Super Dragon Brothers Four

"(W) Yoshiki Tanaka (A) CLAMP Four teenage brothers have amazing secret powers. However, the boys soon discover that someone else knows their secret, and has dark plans to use their powers to take over Japan and then the world! To save mankind, they'll have to fight against their wicked uncle, crooked politicians, and a corrupt police force. They'll also discover the secret their grandfather concealed until his death - the four boys have the power to transform into dragons and control the four elements."