The Hero Is a Girl?!

I had a crush on my campus idol Luna.
And one day the girl belonged to me flesh and soul,
but not in my way, we exchanged our bodies.
I became her! And her fragile body and D cup were all mine!
All this is to blame a weird guy claimed to be a magician from another world.
And he called me Hero who was to save the world which was in danger.
So the Hero has to save the world meanwhile protecting his/ her body from bad guys and lesbian girls.