Blue Dragon

As Shu's village was being attacked by an unknown enemy, he and his friends Jiro and Kluke decide to defend their home. They soon meet warrior Zola and receive the powers of Shadow, an ability that lets them transform their shadows into powerful monsters. Shu receives one of the most powerful monsters, Blue Dragon, and they all set out to defeat their enemy.
All about Blue Dragon http://bluedragon.wikia.com/wiki/Blue_Dragon_(anime)