Reason
Zenitsu Agatsuma, the Lightning style Demon Slayer from anime, Demon Slayer
or, Kimetsu No Yaiba.
As you might have seen in the flashback scenes of the 1st Season of Demon Slayer, that Zenitsu's hair was originally Black before he became the Demon Slayer. So, how did his hair turned yellow?
As you might have seen in the flashback scenes of the 1st Season of Demon Slayer, that Zenitsu's hair was originally Black before he became the Demon Slayer. So, how did his hair turned yellow?
Actually, the answer was also shown in Episode 12 of the 1st Season, Zenitsu
was tired of the hard training of Thunder Hashira, Jigoro Kuwajima, so he
climbed up a tree and started crying. Jigoro was convincing him that he has
the ability to become a Demon Slayer, at that moment lightning struck the tree
and his hair turned yellow.
Anime Scene
Here is the scene from Demon Slayer, where Zenitsu's hair turned yellow.