Majokko Kumi

Kumi is an ordinary Japanese teenage girl. At least she was ordinary until one day, walking back home, she spotted a shiny object falling from the sky into a nearby forest. Upon examining the object more closely, Kumi found a cute rabbit-like creature, who called himself Popp claimed to have come from a magical world. Popp granted Kumi the magical ability of shape-shifting: turning into an adult male of her choice... an ability Kumi will need in order to fulfill her mission: sexually satisfy female students and teachers from her high school...

[From Moby Games]