So is the monster pet…

The monster with the father? The long ahh neck looking thing?

Ya. I think it could be the ghost of her dog. It looks wild but maybe ???

That honestly would explain why it's in the house

Why does it look like a deformed horse tho? Actually what deforms a ghost? Michiru's dad and the cats look normal in their ghost form

so my theory is that its because francios died so long ago. if he died when mikos mama was in highschool hed be dead probably at least 30 years, maybe up to 50. even though he looks like that we already know hes a protective spirit too. there is one flaw here though and thats the chapter with the old man in the hospital. his wife and child were waiting for him in the afterlife for much longer. maybe it has to do with intelligence or location, since the hospital was a "hot spot". could also have to do with francios obviously eating other spirits.

I like the idea of the more the spirits eat, the more they get deformed. The dog, being the mother's protector, would always eat the bad spirits around her that's why he looks like that