Those have been there for years. You see them when you have an active search and are there for quick refinement.
Say you're searching kantai_collection and you see a nice no_legwear picture and you want to see more, press the + button and now you have a kantai_collection no_legwear search. Alternatively, maybe there are some guro results and you don't want to see that, press the - button and you now have a kantai_collection -guro search.
We can't seen enough to even qualify for the more ambiguous "No Panties?"; there are various panty designs that don't cover every last square inch of a girl's buttocks, and that's before getting to the actually risque designs.
If you look closely you can see her panties. There are just a little extra lines but you can see then.
...Murakumo?What.No, just that... you're looking like you're pretty cool there.N-Not at all! Yeah! It's just great!smuuuugMurakumo's Coolbiz.Coolbiz, yes.
Got a problem with that?Taking a second look at it, that uniform with bare legs...maybe it is pretty lewd.
[Hatsu]