My Inheritance Is a Monster

After inheriting my aunt's old apartment building, I was woken up by strange noises from the top floor in the middle of the night. I picked up the steel pipe and went upstairs, where I found a handsome silver-haired man in period costume angry at my WiFi. The red light in his eyes was terrifying: "Mortals, won't you kneel down when you see this king?" I silently raised my phone: "Trespassing, damaging property, intimidating landlords... Do you want to know about the lawyer's letter?" Later, when he signed the rental contract while covering his eyes that were sprayed with pepper spray by me, his tail almost scratched the sofa. It wasn't until the Heavenly Master who was chasing him came to visit me that I knew—— This dilapidated building was originally his prison. And the keychain around my neck is the ultimate authority to open all seals.