I Slept with the Demon Lord and Ran Away

(Cold-blooded Demon Lord x pure-hearted young succubus)

Yue Cang is a succubus. On the night he came of age, his demonic power leaked out, and he urgently needed essence to suppress it. In the mountains, he encountered a cold-blooded Demon Lord who had been cursed by another thousand-year-old succubus.

In the throes of passion, the two ended up in bed together. By the time they woke, dawn was breaking... The Demon Lord looked at the young man curled quietly in his arms, and his perpetually tense expression softened a little.

Yue Cang looked pure and clean, with none of the seductive allure typical of the succubus clan. His personality was simple and quiet, too.

The Demon Lord assumed he was a frail human and took him back to the demon realm, where he doted on and pampered him as compensation.

At first, they saw each other every five days. Then the Demon Lord began taking him along every day. Until one time, with no outside factors at play, the Demon Lord and the young man did it again...

Yue Cang opened his eyes to find himself in the demon realm. He learned that the man was the Demon Lord, feared across all four realms, and that the ordeal had been engineered by one of his own kind.

Afraid the other man would discover he was a succubus, the already obedient Yue Cang became even more compliant.

And then, on an utterly ordinary day, he quietly slipped away.

When the Demon Lord found Yue Cang again, the young man was chatting happily with another man beside him, their words and gestures all quite affectionate.

But when he saw the Demon Lord, he shrank back and hid behind the other man.

Premise: Sincerity is the cure for stubborn denial