Wasn't Kuwana's fault in the first place about Yatora's rash?
I remember she "poisoned" another girl contestant during/before the first test, I may remember it wrong tho it's been such a long time.
Still, seeing her going out of her way to help Yatora with his art supplies it either means she feels responsible (rightly so) and wants to make amends or maybe she's just trying to avoid suspicions in the future.
Either way, I think the whole point is now to make Yatora understand he needs to always take care of his body.