Roshutsu Kairaku 2 ~Asoko no Oku made Misetagaru Koibito na Doukyuusei, Tachibana Mizuki.

Mizuki Tachibana is Mizuki's classmate, who became his girlfriend recently.
She happens to learn the pleasure of exposing herself, and he takes photos of her walking naked in the street.

[From DLsite English]