Sometimes, I hate it when my guesses turn out to be right.
So... now that Mr. Sleaze managed to get himself designated as Pixy's "official" photographer, it looks like he's going to have a lot of opportunities to pester Yumika for a nude photo session.
And given Yumika's attempts at striking cheesecake poses in the bath, it looks like she's actually considering doing it.
I'm guessing that Mr. Sleaze will manage to get his way in the end by getting Kouno interested in posing -- which will in turn make Yumika insist that she be the model instead of her "rival". That, or Edo does something absolutely stupid and thoughtless, which pisses Yumika off so much that she agrees to become Mr. Sleaze's nude model.
Once again, I really hope I'm wrong.