I'll Avenge You

As you can see they are both injured, but Azusa is the one who took the emotional trauma. 

Yui is unwillingly involved with some bad people; a gang to be more exact. The main thugs of the group usually keep away from Yui's friends and family, but the lower-class lackeys aren't aware of that. So, because of Azusa's terrible luck, she was jumped by a group of lowly thugs in some deserted area(I'm not sure where exactly yet). 

However, Yui happens to come across this while running a particular 'errand' and sees a knocked out Azusa. Since Azusa was already unconscious by the time Yui found her, she scooped up Azusa into her arms and proceeded to take her to back to her house and get the injured kouhai all patched up. While walking back, Azusa's muddled mind unconsciously reaches out for the comforting hand on her shoulder; although she wasn't quite sure who was carrying her at that time.

However, Yui pays no attention to this as she only has one thought on her mind: "...I'll avenge you..."

Ohhhhh, I can't WAIT to type up that part!