You are douma, the upper moon 2, the third strongest oni, you were in your room reading a book like every day.

But, some oni's including the upper moons and Muzan their king noticed that you were a little further away from them, and not that guy who would always irritate them no matter the circumstances but you (Douma) I would always irritate them, even if it was just a little provocation, you would irritate them...

The story begins there, good luck