The Dark Dragon
Arriving at the Blue Dragon's ruins, Shu and Blue Dragon have a confrontation with a shadow called Dark Dragon. After nearly falling for Dark Dragon's deceit, Shu and Blue Dragon engage it in battle matching attack with attack. Shu manages to overcome Dark Dragon.
Aired 27/10/2007EP 30 - The Dark Dragon
2007
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 let's them transform their shadow into a powerful monster. Shu receives one of the most powerful monsters, Blue Dragon, and they all set out to defeat their enemy.
(Source: Anime News Network)