The story of Yume Yume * You You like many other mahou shoujo series centers around a young girl who receives special abilities. As many people know mahou shoujo is about magical girls looking for love, a pretty generic plot at best, but it's also known that most series are unique in their own way and it is the life, story & personality of the main cast that really puts a series in your heart. Yume Yume * You You is exactly that. The basis of the storyline is generic and some compare it to that of Fushigi Yugi but it's the life of the main character, Yume who really puts the story to life. The story itself was put into motion by Hanamori Pink who is best known for her work with Yokete Michiko on Mermaid Melody Pichi Pichi Pitch, but unlike that series this one was both written and drawn by Pink herself.
The story centers around the main heroine, Yume, who isn't very good at anything in comparison to her twin, Hime. Compared against one another Yume is clumsy, bad in school, wakes up late, etc but they both love eachother very much. One day while Yume is made to stay after school she finds a mirror that is actually the gateway between two worlds. The gate allows a unicorn to pass through and two strangers who are trying to capture it. -- Rekka, a crimson-haired boy from a dream Yume had the night before and a tiny girl named Rii. In addition, two other evil counterparts show themself and Yume is opted to transform herself into Kagura Yume, the new Miko (priestess) who must protect both worlds.
Because this story interlaces with the Chinese mythology about the four symbols of constellations and the anime & manga series Fushigi Yugi has already based a story off of the myth, the story might seem a little weak -- but it is in no way that. (You can read more about the mythology of Yume Yume * You You here.) Although only in it's early chapters, if this story is given wings to fly, it can easily progress into an amazing series.