Why Does Future Trunks Have Blue Hair. He is bulma s son so he would ha. After that chapter and for the rest of the manga bulma s hair was purple.
Besides they could have just given future trunks longer hair to make him look more different to present trunks. Kid trunks hair was also blue and then when it was animated they fixed it and trunk s hair was back to being normal purple. This even leads to some characters acting like he had always had blue hair as sort of a hair retcon for the character.
After that chapter and for the rest of the manga bulma s hair was purple.
This would lead to a number of new theories about why trunk s. This ties in with future trunks who also has purple hair in the manga and the anime. The studio originally made a mistake with bulma from the dragonball days. Literally no reason to retcon his hair color.