Rukh is one of the anthropomorphic beings from Rashkuta, a town whose inhabitants were cursed by the Devil King. Their former lair was where the Rotten Sea is now. Rukh and his brother found the orphaned Young Boy, so the two raised him like a member of their family. One day however, they were attacked by the Abyss Lords, who kidnapped Young Boy. Rukh's brother, worried, went to the Rotten Sea after him, but ended up in a coma.
Rukh is found in Rashkuta caring for his dormant brother. If the player has Sarah or Young Boy in the group, they will heal Rukh's brother. Out of gratitude, Rukh will offer to join the group.
Rukh is notable for his very high LP (36), the highest in the game. Because of this, Rukh is the ultimate tank character and the best candidate for Dragon God. He always come equipped with a Tunic which can't be removed, so your best bet is equipping him with full body suits and leaving him in the front in a defensive formation.