You have to unlock Mason and Emerald animation.
100 days ago(+2)
There are a few things you have to do.
1.Make sure the girl in blue uniform is not in the next room.
2.If she is not there talk to Emerald and leave without buying anything. If you buy anything even once you have restart the level.
3.If everything is done correctly they will engage in sex. You have to wait until bar below her is filled completely.