How do you max your style by buying premier balls?

I know you buy one at a time, but how exactly? Buy one, close everything, talk to her again? (that's tedious as fuck)

Or do you just buy one, then buy one again, and so on, without leaving the menu? (that would make buying 100 or whatever ot the damn things easier)

I already finished the game and everything but the stone shop only has 3 shitty stones, and yes I've worked at the holel, battled at the restaurant, went to museum and listened to audio clips, used taxis countless times, I mean come the fuck on.