First, a teen would think that being a sub and a masochist are the same thing. I would have thought the same before ch 6, but when you see that Koguma wants to be teased more you get that the fact is actually there. Obviously she's happy when Hino is nice, that doesn't change the situation and you see that Hino likes to dominate her, because her reactions are cute. Koguma almost reaches orgasms and everything there totally looks like a play that they have in secret in that place. Just because they keep it low because they are young doesn't make it less BDSM. The only difference that you have with the couple from Virgins' Empire is that they are both aware that that's a BDSM play.
Ah... that "what teens think" thing was just a reference. Nevermind.
I see absolutely not a single hint that Hino is into domination. She likes teasing Koguma and obviously has a dirty mind (hence why she wants to see her panties, touch her etc.) She is just using Koguma's goodwill to get what she wants. I know that may sound like a dom, but it feels more like a coincidence here (in universe of course, the author is clearly playing with BDSM tropes on purpose). She doesn't mind being on the receiving end either (remember the motivation "button"?).
It's just a bit rash to call teasing "domination".
I also dislike that cat play is always treated as a dom/sub thing.
Koguma is going pretty far on Hino's requests and her reactions do show that she might be into humiliation a bit (hence why everyone calls her an M), but it's more so that she just obviously has a crush on Hino and wants to make her happy and hides it behind her duty as a class pres. Now I'm not saying that there aren't any "obligational subs" out there who just do it for their partner. I'm just not sure the author thought that far.