Yeah there are not many cloth options for now (usually one or two per breast size, for bigger sizes), so the tank-top you reference could be the only one available for a certain breast size. If you are somewhere around levels 60-70, the '?' could be for bigger breast size clothes, which become available later in the game.
Hmm; in that case (having poked along a little further), I suppose the answer is that I'm vaguely disappointed in the selection of clothes for larger breasts. Huge breasts (size 'L' implants) are a nice size in terms of aesthetics, not to mention being the biggest size that Tsumiki likes. Unfortunately, they fall into the gap where school uniforms, T-shirts, and the Big Bikini Bra all just became unavailable, and the only tops available for it are huge bras and the tank tops that it shares with big breasts (size 'M' implants).
A few other thoughts:
It's mildly irritating that patrons in the male-leaning side often demand naked legs alongside male clothing. Naked legs combines just fine with female clothing (the schoolgirl skirt is short enough to count as both), but it's contradictory for male clothing, since the starting male shorts aren't actually short enough to cover the legs, and no other clothing covers the combo (unisex shorts come close, but patrons are often picky about this). Sure, I get that you can't satisfy everyone, but at least any given patron ought to not demand something impossible? This could be fixed either by making the existing male shorts expose the legs like the unisex ones (possibly shortening them just enough to expose the knees in the process to make this reasonable), making a new shorts item with those properties as an unlock in the level 20-30 range (around the time when a new player might be doing 'Boast' and 'Exercise')... or simply just forbidding patrons to have that particular combination of interests.
There are multiple rooms with
very specialized requirements that put the player into the Exotic appearance category for meeting them, which makes all love interests dislike the player. Unfortunately, patrons in those rooms still expect sex acts; this isn't impossible to get past (since toys half-count, and guests often demand contradictory things), but it's hard to satisfy them. This wouldn't be a problem if there was at least one love interest who's open to a partner with an Exotic appearance. Sensei would be the logical choice here; as the most openminded partner, she's Best Girl anyways. Alternatively, it might make sense to sort out the distinction between the sort of Exotic that combines large breasts and a muscular frame (call it 'Amazon'? Kuro might appreciate this category, given how his primary interest is breasts), and the sort of Exotic with extremely feminine features but a flat chest (call it 'Femboy', or maybe just extend 'Trap' to cover that region? this might appeal more to Sensei).
Also, given the wildly fluctuating requirements at those levels... I was able to find that I had a 100% match on primary and secondary interests for the 'Double' room, but wasn't able to get into it; it wasn't until further experimentation that I found they also wanted a small penis to permit entry (not listed in the requirements?). For that matter, patrons in the 'Double' room often
demand male clothing, but prefer 'Wide' hips which make it impossible to wear male bottoms. It feels like the requirements of this room ought to prefer 'More' hips instead, to actually make this possible... but if the player meets all of the requirements except for having 'More' hips instead of 'Wide', they aren't actually allowed in the door. This contradictory pickiness makes this a frustratingly luck-based experience, even when I'm far enough through the progression that the room is just short of being counted as "Low-Level".
EDIT: it doesn't help that half the time, the audience in Double wants to see a naked female chest (which the small chest the room wants doesn't actually count as), a naked female bottom (technically fair, since it's supposed to be a girls' room, but no less annoying since the player can't actually manage the feat), or female clothes (contradicting the other guests in an already difficult room). Is some kind of treatment or prosthetic to let the player fake a more feminine groin planned?
).
