The Willful Demon King's Contractee

A boy, broken by fate, sold his soul to a dead demon king as he lay on the verge of death.

Demon King: "Mortal, give your soul to me..."

Boy: "Y-yes... Even if I have to sell my soul, I'll make them pay in blood."

Dawn returned to the horizon, and a beautiful fish-belly white glow spread across the sky.

The endless burning flames of karmic fire finally died out. A breathtakingly beautiful girl lay among the ruins; no matter how countless the red strands of fate, not one could rival her.