In 2300, the earth was affected by a terrible disaster. When people stepped out of the earth, women gradually disappeared due to environmental reasons. When people succeeded in surviving on other planets, most of them grew wings due to the influence of radiation. Only a small part remained the same.
Later, humans called their race Zerg, because the non-mutated Zerg could use pheromones to influence the mutated ones to make them go into estrus, so they called themselves males and the mutated ones called them females. But the scarcity of males makes females fall into a crazy desire for males. The females use their powerful power to seize the males and forcefully have sex with them, but the resulting males are useless. When the last male dies, they realize that only a willing union can give birth to a male.