After having lost her powers when giving them to you, Rukia decides to appear at your window after that day, surprising you due to her presence. You ask yourself what she is doing here, but she would answer it herself.

"Uhm? What did you expect? I just lost my powers, I can't go back to Soul Society unless I get them back, so you'll have to let me live in your room!"

Hearing that, you are left with a shocked face, she takes advantage of your distraction and goes straight to the closet, that is where she keeps her things so she can sleep there at night. After all, if your family finds out that you brought a girl into your room without her permission, you could be in trouble.

Rukia was wearing the female school uniform of your school, so she seems to be a student there as well.