Black Dragon

Black Dragon is the strongest of the 4 black saints. Before Black Dragon's death by Shiryu's defeat, he was finally convinced to believe in "Friendship" that Shiryu kept telling him about and stopped Shiryu's bleeding before he died.

Black Dragon (the hidden one)
He is The blinded elder twin brother of Black Dragon. He appeared in manga only. Shun's nebula chain noticed the hidden Black Dragon and Shun warned Shiryu to watch out for the one in hiding. Shiryu finally realizes the existence of the hidden Black Dragon and defeated him with one hit.