This Page by Hecate
Shadow Lady is Aimi's alter-ego, but she could be anyone's. She is created when someone applies the magic eye-shadow, whether they be male or female. She has 8 forms, only 5 of which are revealed during the series: Normal (black eye-shadow), Cat Shadow (red), Bird Shadow (blue), Bunny Shadow (yellow), and Super-Pro, which is effected by screaming "Super-Pro Change!". Each of the animal transformations allows her to take on the attributes of each animal. (Ergo she can fly, climb, etc.)
Shadow Lady's name adds to the fun plays on words that fill the story. She is Shadow Lady because she lurks in the shadows of the night, mysterious and so forth. She is also Shadow Lady because her true identity is in the shadows. And she is Shadow Lady because she puts on eye-shadow to transform. :)
Shadow Lady has a very definate personality. This varies from the French to the English translations. In French she is flirtatious, teasing Doryh, Bright, and the others. She enters with a cry of "Coucou tout le monde!" (Yoohoo everyone) and flits about emotions lightly. In English she's a little more heavy-handed, exclaiming that things "turn her on" and saying "yo baby". However in both languages she is fun and just out for a good time. Shadow Lady doesn't care about other people. Her only goal in life is to have fun.
Shadow Lady is a fun character. I think she is the ebodiment of every she person's wish. She represents escape for Aimi. Also I think it's neat that her One True Love's name is Bright. The atraction of dark to light and vis versa again! :)