Kiku: I shouldn’t give you this information, but I know your suffering.
Demons are the most powerful kind of entities, and you should be especially careful. If possible, don’t even get close - I was lucky the Demon I fought only took my leg. If it hadn’t been for my uncle, my aunt and my mediums I would be dead right now.
If you still want to fight it for some reason, well… good luck. Demons are so powerful, they distort reality and bend the laws of physics, creating time and space vortices which can suck you in. They can play with your memory and with your very existence if they are sentient enough.
Find out if the Demon is attached to an object. Then exorcise the object. It may require a sacrifice - but we can never be sure.
I don’t mess with Demons anymore, so you’re out of luck if you came here to hire me. I’m sorry, I would never risk my Maiden and my Guardian’s life in a hopeless battle. I hope everything goes well to you.