Lemon Angel

The protagonist of Lemon Angel is Tomo, a high school student. The plot involves Tomo meeting her friends Erika and Miki, only to become trapped in a magical dimension with her friends gone. Tomo must travel to various worlds in order to find them; these worlds have varied themes and settings, including an alien attack on a spaceship, a country populated by giant sexually abusive mushrooms, a realm that changes Tomo's gender, etc.

[From Moby Games]