Revenge's passion overcomes hate, and a dragon becomes the warrior's steed.

Breaking into the castle through the closing net of the Imperial army, the mortally wounded Caim encounters a shocking spectacle. Before him, captured and fettered by the Empire, is a crimson dragon, a creature of the same breed that slew his parents. Eyes made blind by rage, Caim lifts his sword to stroke dead the hated beast.

"Kill me if you desire..."whispers the dying dragon.

Caim pauses, his sword still raised to deliver the death blow. And at that moment, he makes the decision to live, and demands from the dragon a pact. Through the pact-price he must pay is undeniably great, a union with the dragon would not only allow him to survive; it would afford him the power to exact his terrible revenge on the Empire.

When a human and a beast exchange hearts and forge a pact, they become "pact-partners." It is said that a human and his or her pact-beast are equal in strength to an entire nation's army, but only a select few may ever be worthy of tasting such power. The human must pay a terrible price for a pact by sacrificing a treasured function of his or her body.

But the mighty dragons comprise a noble race that does not easily submit to the dominance of another. Even though captured and on the brink of death, the dragon's pride is still strong.

"Tell me. Do you still want to live, dragon? A pact! There's no other way."

Caim will not be denied, and little by little, the dragon begins to consider. For a moment that seems like an eternity, the two proud adversaries glare at each other. Then the dragon makes a decision.

"Yes. A pact..."

Caim and the dragon exchange hearts, and the pact is sealed. From now on, dragon and warrior will, for good or for ill, share the same fate.

Transformed into a rider of dragons, Caim turns toward a battle in which is wrapped the fate of the goddess and of the whole world.