I think Cid's interpretation in the notes is pretty correct. Anchor-lady is much sharper and more emotionally mature than even Yumika. By the same token, though, I don't think what she's after is an emotional or romantic relationship. She's interested in earning Shunske's respect because her daughter likes him.
Miya EARNED teh bonk she received this chapter. Also, it's pretty clear she enjoyed the situation. Miya knows how to S, but is a bratty M, most definitely.
(Also, Hotwax Dominatrix Yumika is pretty hot.)