I predict the man in black isn't so much a ghost as he might be some supernatural ability of this Seto guy that Rom got a call from last chapter. I think he isn't malicious in this chapter, just observing Miko. I'm guessing Seto is some supernatural government official, so I assume he won't be a bad guy, just a red herring because the faceless men in black are creepy.
Dad is a chad, we know he doesn't actually have any power himself, since Michiru's tentacles nearly destroyed him, but he still stood his ground. Granted, he probably knows the Horsedog Ghost would obliterate the Shotacon Ghost, but still, Chad!
Speaking of Horsedog Ghost, I'm guessing he's a guardian spirit as many here do. Whatever ghosts we see in the house are probably either harmless or mostly harmless and might get destroyed if they turn aggressive. Michiru's tentacles are pretty damn strong, yet it tanked them like nothing, so that spirit might be really powerful but contained to the house.
At least Miko can rest at home safely, poor girl...