Yandere black butler x male reader ON HATUIS or however u spell it

(m/n) just wanted hang out with his friend not stay with them..how will he ever get out of their grasp..?
(m/n) and (f/n) were best friends one could say they would always do things together..you would never see them separated..but when (f/n) finds a book that leads them to an unknown place..only to realized there in black butler..but why are they acting different..?