Girl, you're about to reveal a murderer who's gonna have nothing to lose once you do. And when his secret's out and he has nothing to lose, what's stopping him from slitting your throat in broad daylight right on the spot?
You know, Ume can practice his pimp hand on Tan guilt free because he's not a girl. Then send him to the streets to earn him his money back. And Arisu ends up being his #1 customer.
I mean they could just have her appear earlier as a cameo or something and say something like "You wondering why I appeared sooner than I did in the manga? Because I'm Meta, that's why!"
Okay Author, we just want a nice cute romance between the guy and the girl with no annoying-
Author:"I'm gonna introduce the annoying third wheel."
YOU SON OF A BITCH!
Father just needs to realize that if they'll all get married he'd have to learn to tolerate and not to kill at least two men, assuming Yuu is one of the husbands. So it would just make logical sense to marry all three sisters to Yuu, and not have to deal with more sons-in-law.