All of the kits to change your hair can be bought at the Cash Shop, though their availability varies. The same goes for the Color Change Kits, both premium and Novice. The basic hairstyles can also be chosen when you create a character.
Seasonal Hairstyle Kit
Female Seasonal Double Chignon
Female Seasonal Modern Cut
Male Seasonal Modern Cut
Male Seasonal Slick Back
Poetry Hairstyle Kit
This Hairstyle Kit is a Premium Kit, which means that later you can use a Premium Color Kit on these hairstyles.