Some characters have hair colors that are possible, but very uncommon for the setting, like blond and orange in feudal Japan. The show is otherwise realistic, but the writers don't want all the characters to have the same hair colors. This trope shows up mostly in Asian works, since hair colors other than black or dark brown are still quite rare there, but is by no means limited to that part of the world. A black character with blonde hair would be a good example. When hair colors become humanly impossible, we have You Gotta Have Blue Hair. Examples of Implausible Hair Color include: