But she dyed her hair black in Mio and cut it again
it's only been about a year since the beginning of the manga. As an actress (and as the person before me said) she's probably maintained her cut and dye job not only for her personal image but for the acting jobs she's done. It would be very strange indeed if Natsu-san suddenly had long black hair for instance.
i seriously wish that the mangaka would draw kyoko with longer hair or black hair already. it's been like what, at least 1-2 years since she dyed and cut her hair?