I don't know if you guys have been reading the same manga I have, but literally nothing is going to happen between these two. No hamster banana, no train plowing through, not even lewd handholding. Author is just baiting us.
So serious question, is she wearing underwear? Did her senpai wash them for her, or is she wearing wet panties? If she isn't wearing anything under that shirt this situation has some new context. Are these two on the level where they can be practically naked around each other.