She doesn't know where she is. Or when. She doesn't even know how long it has been since Sailor Pluto approached her to bring her to the future and she got lost in the nexus. But she knows, it must have been a long time and that she hasn't even slept for half an hour since then.
And she's tired.
There's a limit time of how long a person can go on without sleeping, even being a youma and in her Sailor Moon form, she has such a limit. And she's reaching it. But it's not as if the nexus has been kind enough to give her a chance to sleep. The space between times isn't a good place to sleep, neither is it safe after what got her lost in the first place, and besides that, the closest to a place where one could sleep that she ended in was a hospital room. There's no way she could sleep in such a place. And so, she kept on moving without bothering to sleep. Trying to get to Elysea and failing.
Her mind is close the break point. If she doesn't settle to sleep soon she'll just collapse, her brain restarting and forcing her to sleep in order to recover. So, when she finds herself in a bedroom, Usagi is beyond the point of caring about being rude or not. She's tired, exhausted and if she doesn't rest soon she may end unable to do anything for a while whether she likes it or not.
She doesn't recognize the room but she doesn't really pay it much mind as she cancels the transformation, turning back to her civilian form and moves to a chair besides a desk. She is beyond caring about being rude for sleeping in someone else's bedroom, but she's not rude enough neither crazy to sleep on someone's bed. Besides, sleeping on a chair isn't comfortable, it should help to keep her brain slightly alert. She sits on the chair and leans against the desk, her arms folding to be used as a pillow... She loses consciousness even before she's fully settled in place.
But still, this isn't her room, neither the room of anyone of her world she may know. But this may be your room, or it may also be an alien room for you. At any rate, there's a girl sleeping on the desk in a room that isn't her own, what will you do?