I really hope that the Masaki will now think that Mikatan is having an incestuous relationship with her brother just so Mikatan can face some form of repercussion for her mind games.
I figure that the author wont go there but wouldn't it be amazing to have Masaki actively avoid Mikatan out of disgust and when Mikatan figures out why, either through overhearing him from her surveillance camera or him telling her, she completely breaks down or freaks out. The only logical way Mikatan can clear up that kind of misunderstanding is by admitting that she's been screwing with Masaki's mind this entire time, ruining her "fun and games" in the process.
It would be so good to see Mikatan get her just desserts for what she's put Masaki through. However, either the author would either have Masaki not think too much about it or have Mikatan spout out some unbelievably dumb excuse that sidesteps her having to admit her wrongdoings, like she and her brother are giving each other really good massages or something absurd like that. Masaki would probably buy anything Mikatan would say because he's not that smart, and that's putting it mildly.