A man who trusted a legend, believes that he could become a demon king by not breaking the taboo with a female for 400 years finally gained a mighty magical power and have termendous strength to be titled as the demon king.
So the Demon proceeded to conquer the world with enormous power to make his childhood dream comes true, 'become a great man' >> 'get a beautiful wife' >> 'be a good father'.
However, although the first dream was achieved, he hit a huge wall trying to make his second dream comes true.
The Demon doesn't want to marry someone by force, he wants someone who loves himself from the bottom of her heart. However the demon absolutely have zero experience with woman since he didn't interact with them for almost 380 years.
This is a story about the struggles of a woman that is going to marry the demon king that holds tremendous power.