If you're into yandere stuff try reading my novel of mine.
The Demon King decided to quit ruling the Kingdom of Arcadia and give it to the humans and non-humans. He no longer has an interest after he had gotten everything he wanted in the world. After he left, his subordinates thought that he was already dead. But it was just his puppet. As for his actual body, he slept in his room for eternity since he wouldn't die.
The Demon King's favorite toy is his puppets. Because of those, he became a total shut-in in his room. While he was in his eternal sleep, the hero woke him up through his dead puppet. Forcing him to come after her, get out of his room, and destroy that puppet.
When he came out of his room, no one recognized that he was the Demon King as he always used a puppet. His subordinates didn't know that he was the Demon King they followed. A new chapter unfolds as he experiences the new world around him.