>>57839761The hair at the back of her head should be the same as the length in front, it just gets tied up into the small low ponytail ORAS May has in both her default and contest outfits. In her RSE outfits with the bandana, the ponytail is just tied higher up then hidden under the bandana, which has been shown in the manga.
The only retarded exception to this is anime May, who is just bald at the back, at least before she got the ORAS contest outfit to fix her hairstyle.
