Trying to remember an animes name

i am trying to remember this animes name but i cant i remember the story tho. this boy has came from the future and is sent to kill a princess wich is a little blond girl and she is headed to a school on a flying ship made out of the earth with her schloss on it and he is flying this mecha only thing tho in the world he is in only femails are able to use these mecha there the only ones able to ride them and he fights and well looses and he becomes Friends with the princess and her servant girl wich has rosa hair and is probly 20 but in the Anime all the people Friends with the princess usually flirt with hm and he becomes her assistant and all and the people who brought him to there world in the prince and he is masked unless he is at his school wich the boy attends. im sorry if its not good enough to Du but pleas if i have to ill tell Du it in another detail pleas help me :(