Saiyans always have black hair with certain characteristics. This is why Goku and Vegeta have always had the same hair. However, this does not apply to the Saiyan means and this truth was known with Dragon Ball Z, on the occasion of the arrival of Trunks of the future in the main timeline.
In both the Dragon Ball anime and manga, Trunks shows up with lilac hair. However, in Dragon Ball Super, Future Trunks ‘hair changes and turns blue like Bulma’s, while Baby Trunks’ hair remains a more purplish color. Why does Trunks have blue and not purple hair and what color should he have in Dragon Ball Super according to Akira Toriyama’s original ideas?
Let’s start with an assumption: Trunks has mom’s hair the same color. This means that in the anime he should have had them blue, while in Dragon Ball Z he has them lilac and only in Dragon Ball Super are they recolored that way. The error arises from the drafts sent by Akira Toriyama to the production of Toei Animation.
In the Dragon Ball manga, Bulma has lilac hair and according to Toriyama this is the official color of the woman, although by now we are all used to seeing her in blue. Consequently, for the mangaka Trunks was obligated to have lilac hair and then, when he sent the coloring for the character from the future to Toei Animation, they formalized the lilac color for the anime, probably not knowing the relationship between the hair of mother and son.
Only with Dragon Ball Super, Toei Animation has decided to recalibrate the situation and make Future Trunks’ hair look the same as Bulma’s in the anime, but inexplicably leaving the child Trunks, who still has lilac hair, out of the question. A similar mistake happened with Vegeta at the beginning of Dragon Ball Z.