Diane (Seven Deadly Sins) and Mount Lady (My Hero Academia) are giantesses, and they are relative rivals. When Diane has Zach as her first human son, Mount Lady wants him all to herself as her son. But they have to fight each other in order to get custody of Zach if it leads a battle to the death. If Diane win she keeps her baby boy. But if Mt. Lady wins she get Zach and unbirth him and give birth to him as her son with a new name.