Saiha

He is the dragon most used by Recca. The Dragon Saiha is the second Flame Dragon with the power to produce a blade of fire that is unbreakable and can cut anything. There are certain parts in the manga where people block against Saiha, but not with a physical object (Saicho uses his aura and energy to surround his sword to hold against Saiha, and Neon uses the sound energy around her flute to repel Saiha as well.). As a human, Saiha is a standard ninja with spiky hair. During his lifetime, his flame took the form of a hawk.

Source: http://flameofrecca.wikia.com/wiki/Saiha

Saoha's human and dragon forms.