Here's the main preview:
It is directed by Takuya Igarashi (Soul Eater, Ouran High School Club), along with screenwriter Yoji Enokido (Revolutionary Girl Utena), and composer Satoru Kousaki (The Melancholy of Haruhi Suzumiya!!!1 :O)
The American premiere will take place in New York Comic Con Anime Festival on October 9, courtesy of Aniplex.
It is the story of a boy named Takuto Tsunashi, who one night just arrived unconscious to a verdant island called Southern Cross because he swam ashore from another place.
He enrolls in the island's high school academy, which happens to conceal a secret 20 giant humanoid machines underground.
3 new TV spots, of 15 seconds each, have been uploaded to the official site of the anime (click the link and it will open in a new window)
Spot 1
Spot2
Spot3