Mercuria: Mizu no Miyako ni Koi no Hanataba wo

Summary

One day, Wataru, Himiko, Ai and Seishuu accidentally fall into a shining puddle on their way to school. When they put their heads our of the surface, they find that they are in another world called Imbruglia. The girl standing in front of them is actually Princess of the country. To go back to their world, they join a magic school...