Each balloon that surround themselves around Mafuyu continuously float around the dark, empty room that she had locked herself in—taunting her with the images of a closed eyed smile on each area. She already knows that her mental psyche is fragile, and these damned balloons didn't exactly help that case, if anything, it just made it much much worse.
But even with the help of her friends and the singers at the Empty Sekai, there's that glimpse of hope that she has been so long trying to reach for. So in a sense, she doesn't need to really hide her truth feelings any more.. At least that's what her heart tells her.
But all of those feelings of nothingness, those taunting closed eyed smiling balloons were interrupted upon receiving a knock on the door, the world that she had supposedly built completely vanishing in an instant as she had woken up from the sudden intrusion. It seems to be that she slept in her school clothes; exhaustion most likely.