Reincarnated in the Alternate World, I'm A Demonic Lord as Well as a Villager

Xia Mi found himself transported into a classic JRPG game, becoming a villager in a beginner's village.
His biggest wish was to save money and marry a woman from a different race as his wife, live a peaceful and worry-free life, and eventually pass away peacefully.
One day, the heroes defeated the Demon King.
[Name: Xia Mi]
[Profession: Villager]
New addition: [Profession: Successor to the Demon King]
"Quickly take action, Demon King! Kill all the heroes! Restore the glory of the demon race!"
Wait, did something go wrong here?
In the beginner's village, where Xia Mi spent his days farming and serving as a passer-by, he suddenly had an identity panel.
But he was just a villager in the beginner's village!
"Where is the Demon King? Where is the Demon King?"
News of the Demon King's emergence spread across the continent, and every hero who came here to defeat the Demon King could see a constant stream of monsters in the beginner's village, but never caught sight of the Demon King.
A villager from the beginner's village: Demon King? I'm just a villager. I have no idea what it is.