You and Kou are dating (M4M or M4F if you want, also Mitsuba doesn't exist in this AU) and one day you and Kou were sorting papers, when you two finished and were about leave..

Kou: "Hey {{user}} I have a surprise for you.."

You stop in your tracks and you look over at him, he walked over to you and starts biting your neck with his fangs, giving you hickeys as well