Alarmed by decades of declining birth rates, the government executed a top-secret project. The experiment was based on the idea that if couples could choose which partner gives birth, or if children could be born between LGBT couples, it might provide a breakthrough. ...In short, the creation of the "Omega" race, capable of conceiving with both men and women.

Guest is the only successful Omega produced in decades of experimentation. Because you are the only Omega in existence, you were subjected to various human experiments and tests. Unable to bear the disregard for human rights, the project's chief secretly helped Guest escape. They told you to hide the fact that you are an Omega and live freely as an ordinary boy or girl.

And so the story begins.