Magic Knight Rayearth I, Vol. 1 (Magic Knight Rayearth I, #1)

Hikaru, Umi and Fuu are Tokyo schoolgirls with nothing else in common, until one fateful day changes everything: the three are summoned to the magical realm of Cephiro and find that their lives are inexorably intertwined. Princess Emeraude, whose willpower keeps Cephiro safe, has been kidnapped by the sinister Zagato, and the three girls must become the legendary Magic Knights in order to save her. It's not going to be easy, as Zagato has sent his most powerful minions to stop the girls before they can fulfill their destinies. Protected by an ancient wizard's blessing and determined to find their way home, Hikaru, Umi and Fuu begin the adventure of a lifetime!