Unmissable achievement, as long as you keep buying decorations for your tower. First off pick whether you're going to stay with Rose or go with Velvet later on in the game. If you're going with Velvet, don't start buying decorations until after you get her, because the old decorations wont count.
Eventually, the minion narrator guy well tell you that your mistress wants to see you in the bedroom. Go there to unlock and enjoy the cutscene.
Thanks Petey 247 for the reminder.