My Contract Beast Is an Ancient Corpse King

In a high-martial world, warriors cultivate through their vital energy and blood. At sixteen, they awaken a "Contract Space" and can contract one monster beast as a combat partner. Monster beasts have five ranks: Mortal, Spirit, Earth, Heaven, and Saint. Each rank has four grades: Beginner, Intermediate, Advanced, and Peak.

Contract rules: The contracted beast and its master are bound by their souls and share a life as they grow together. If the beast dies, its master is gravely injured; if the master dies, the beast vanishes.