In a world where humans have various abilities and coexist with various races, Kale is a boy who has been treated as incompetent due to a lack of an ability. After helping a vampire princess, Kale discovers that his ability allows him to become the strongest of any genus once blood is shared. This power allows him to adapt to the characteristics of any of the races. With this power he has the potential to become the king of all races, which draws the attention of all the races whether their intentions are good or malicious. Thus, the one once called the weakest incompetent will become the world's strongest!!