anime history - When & where did the unnatural hair color aka You gotta have blue hair trope originate? - Anime & Manga Stack Exchange

I specifically want to know which manga or anime started the trend, so I can reason from there to the how question, in order to not make general assumptions. There was a time in manga/anime where

OK K.O.! Let's Be Heroes (Western Animation) - TV Tropes

You Gotta Have Blue Hair, Tropedia

HOLiC (Manga) - TV Tropes

Why is it that anime characters are often drawn with unnatural hair colors? (pink, red, blue, and similar bright colors)? - Quora

Anime Hair Colors: Do They Carry Any Significant Meaning In Japanese Culture?

Why do the main characters in anime have unnatural hair colors while background characters have natural colors? - Quora

anime history - When & where did the unnatural hair color aka You gotta have blue hair trope originate? - Anime & Manga Stack Exchange

Did the trope of 'You Gotta Have Blue Hair' originate in anime and manga, or can it be seen in enough older works to determine a different origin? Is there any official

Did the trope of 'You Gotta Have Blue Hair' originate in anime and manga, or can it be seen in enough older works to determine a different origin? Is there any official

Why can anime characters be born with any hair color? - Quora

Did the trope of 'You Gotta Have Blue Hair' originate in anime and manga, or can it be seen in enough older works to determine a different origin? Is there any official

Why do anime and Manga characters always do exaggerated expressions? - Quora

How they determine the character hair colour in anime? . We know that manga usually black and white but in anime adaptations we can see the variety in the hair colour. Is

Why is it that anime characters are often drawn with unnatural hair colors? (pink, red, blue, and similar bright colors)? - Quora

Did the trope of 'You Gotta Have Blue Hair' originate in anime and manga, or can it be seen in enough older works to determine a different origin? Is there any official