12 AM is the 2nd hour (1st "real" hour in terms of gameplay) of Emily Wants To Play.
When the clock strikes midnight, Emily's first doll comes out to play, Kiki. Kiki is a pale-skinned doll with black hair and a black dress. She will randomly spawn into the room you are present in; a giggle can be heard when she appears. In the kitchen, a sign can be seen hung on the wall, stating to not look at Kiki, which is a lie to trick the player. When Kiki spawns, it's best if the player starts a search for her immediately, since the longer their eyes are averted from her, the closer she comes to finding and killing the player.
Kiki likes to turn the lights off while she is active. The flashlight, hidden randomly, is helpful as she will try to turn off the light in the same room as the player, although she has been known to turn off the flashlight as well.