Yume Yume * You You is about Yume, a girl with a twin sister who hogs the spotlight. Yume feels inferior to her sister, she's more popular, smarter, and prettier.

One day, while slacking off on her studies, Yume discovers a mysterious mirror that releases people from other worlds into hers! Yume must transform into Kagura Yume and save both worlds!

credit: manganews.net