After the New Era, the social structure was greatly reshuffled. Standing at the top of the pyramid were humans who gained strength and could transform into beasts. However, their shortcomings were also obvious. Their fertility dropped to freezing point. After years of exploration, the new humans discovered that there is a type of man with a super strong physique among ordinary humans. When combined with them, they are much more fertile than ordinary women, and their offspring have inherited excellent genes. Such men are called the third gender, but the existence of the third gender is extremely rare. From then on, there are three kinds of people in the world: ordinary people, new humanity, and the third gender.