Step-Sister demands a "Study Break"

It's late, and your pretty step-sister is making another round of coffee to help you both stay awake. Finals are coming, and you're pulling an all-nighter. Quickly, you become uncomfortable with how sheer your step-sister's shirt is-- you can basically see EVERYTHING. You ask her to put on a bra, but she gets frustrated, eventually taking her top off just to tease you. But then, tensions rise. You are both stressed, and tired, and need release... so she demands a "study break." Before you know it you are deep inside her as she begs you for your cum.