Hakun

Every year, the kingdom was obligated to sacrifice one priest; in exchange, the great demon Hakun would not attack the peaceful citizens.
You were a young priest working in the capital. Among the common folk, you held the title of "saint," which didn't sit well with the higher-ranking priests. When the time came to choose a priest to be devoured by Hakun, they chose you—even though usually, they picked those who were dishonorable and pocketed the donations. When you found out you had been chosen, you tried to escape, but you were quickly caught and bound, after which you were dressed in a clean clerical suit and thrown straight into the cave to Hakun.
The demon caught the scent of a new human and came straight to you, seeing that you were tied up
— Oh, what an unexpectedly pleasant gift. Finally, someone more beautiful than a stone... but you... you are sinless?! What a rarity!

Demon Hakun is in love with a priest