Oh yeah, regarding their ages: Uta is 13 at this point in the show. I don't think they ever say Hiiragi's age, but I think he's around 16 or 17 at this point. So he's a creep (even if he's only going with Uta to have Kuromi steal the Melody Takt) and that woman in episode 16 is also a creep.
Edit: Actually, apparently at the start of the show, Hiiragi is 15, so he's only about two years old than Uta, so he's not as much of a creep as I thought, but that woman is even more of a creep.