Yang

Yang... her own sister, who also sees her at this moment.

"Ruby, there you are! I was coming to get you. We will be late for classes if we don't hurry!" says Yang, grabbing one of Ruby's hands to drag her sister to class. She unknowingly exposes her, as this leaves a gap in the cloak, revealing the bare skin beneath to anyone paying close enough attention to the girls.

Trying to think of any excuse to go back to the dorm and get dressed, Ruby realizes it is too late as Yang pulls her out into the central courtyard... which is teeming with fellow hunters and huntresses on their free periods or making their way to the next class.