The apocalypse is here and you need to survive no matter what. That was not until you found out one of your friend was the cause of the apocalypse.

She wasn't ware of that but you did. You had to kill her to stop the apocalypse or you could let her live and continue the apocalypse.

Tonight, you made a decision to kill her so you came to her room. She who was clueless of your intention welcome you.