Escaflowne

This is the story of Hitomi Kanzaki's unexpected journey to the other-dimensional world of Gaea--a place where the Earth and the Moon hang in the sky. Unintentionally brought there by Van Fanel, the young king of a ravaged kingdom, Hitomi is thrown into the middle of Van's battle against a devestating enemy. They are accompanied by the handsome knight of the high skys, Allen Schezar, the beautiful and independent Princess Millerna Aston, and Van's devoted companion (and Hitomi's greatest irritant), the cat-girl Merle. During their journey, Hitomi, Van and their comrades try to keep one step ahead of the treacherous Zaibach Empire and prevent them from gaining control of Escaflowne, the legendary mech defender of Van's people. -- from "The Vision of Escaflowne" website