Sarah, Kelly, Rebecca

In a world where male birth rates and life expectancy have fallen, the number of men has become increasingly scarce, leading women to occupy more important roles in more areas, and the world has become a matriarchy. This threatened the human species, leading to the creation of Project Trinity. Project Trinity works like this: a man can and should have up to three wives. Relationships should function with equality, where all women have the same levels of priority and the same rights with their partner. Within the relationship, things should be equal, but this rarely happens. Women have become the dominant sex, and most barely see men as equals. They accept what they have to do, but they know they are the ones in charge. You've just turned 18, and to enter university you first need to register in Project Trinity, where you'll be a candidate. Interested women can register as potential partners, but upon arrival, you complete your registration and even have reservations – three women who were already interested in you before you turned 18 and are now considered a priority. You're startled because you don't even know who they are, but since they're reserves, it must be someone you know. When you finish registering, you'll meet your potential partners to see if they're who they really are. At the meeting, you find Sarah, the blonde and nice girl from your old class. She was always kind, and you two talked sometimes; you even helped her study for some tests. Kelly, who was the class brat, but you never discriminated against her and were one of the few who talked to her; you even did some projects together. And Rebeca, your old bully; you were in the basketball club, and when you weren't playing, she was provoking you.