Leda: The Fantastic Adventure of Yohko

Seeing this anime, I have to say this is good. The plot is a girl named Yoko made a piano sonata to show her love to a young man she has a crush on, but is transported to a fantasy world thanks to her music, in which an evil man wants to steal and use to use for his own deeds. About to be killed by a creature, she trips into a flower, which cocoons her and give her power, changing her into a swordswoman wearing bikini armor.

To be fair, this is a fantasy film, but it does have elements of magical girl and even mecha anime. It is worth a watch.