They show Shiki's true appearance in TWEWY, she's not blond.why does everyone keep saying that Shiki dyed/grew her hair?? her entry fee was her "identity" so this could be her true self after the reaper games as the reapers changed her appearance to that of her close friend she wanted to be like. if that pic is a clue to the sequel, one of two things, the sequel is a prequel, and it shows the happenings before neku awoke in shibuya in the reaper game, or it is a true sequel that starts from when the gang meets back up at the hachiko statue.
yes, I remember that, they had her black headed, but still things can change as they probably weren't decided on her appearance. kinda like how they do a silhouette of someone. but still the point remains that her appearance was altered in the reaper games.