You Are the Boundless Moon

The little princess, raised in luxury in Nancheng, fell for the dreaded King of Hell of the capital at first sight. She demanded a marriage contract, binding the two of them together from then on.

Yu Nan had always lived in a barren, dark world. He had never imagined anyone would save him, and thought he was destined to sink into darkness forever. But one day, a delicate young girl came bursting in, bringing a dazzling light.

From then on, his world had light.

[One-on-one, both pure; she pursues him. A frail little princess vs. a world-weary young nobleman]