Monster Fusion

Humanity fell long ago, when magic returned and with it Spirit Beasts, at first the humans tried to fight the Spirit beasts thinking they were creatures from their old mythologies, but then the dragons appeared and stopped the fighting by warning the humans and Spirit beasts of the real threat, an advanced civilization, totally bent on their annihilation, and thus was born the contract, a written living accord that allowed humans to gain the powers of Spirit beasts through bonding with them either with a familiar bond or by taking a monster seed and becoming part monster. soon after the world grew, and the bloody past was forgotten in order to fight the new threat.