There is no NTR, but you can share Anna with most of the people in the game. You will be given choices of dialogues and in certain events you will see that certain dialogues will lead to Sharing Route or Romance Route.
You are able to choose naughty, bold dialogues and constantly pushing Anna to expose her sexual desire ( Slut / Sharing Route ) or loving, caring dialogues that makes Anna becoming more loving towards you ( Romance / Pure Route ). As you chose the dialogues, you can see the emoji on the bottom right of the screen to see which dialogues leads to which Route.