Tsundere Much?

Yoshida Miyako and Ookami Arashi have been friends ever since childhood, which is seemingly impossible to others because of their different personalities; the first being a timid yet cheerful little girl, while the latter an arrogant young boy. Neverless, they manage to keep their friendship intact. But will Arashi moving away change all that? Years later, both now in their teen years, they meet again, and Arashi is still the same as he ever was.. as Miyako says,
"Once a tsundere, always a tsundere!"