Yeah you get there after you have been to Order Realm. In Order Realm you get Hotaru to goto Outrealm to defend the walled city. You follow him to Outworld and go through a few missions before you get sent to that group of houses by Kano when you meet him in the Living Forest. You are basically a prisoner of Shao Kahn at that point. Then you can get Li Mei, just walk into the house and you'll see her.