Idolmaster Xenoglossia

The show centers around mecha and re-imagines the ten prospective idols as fighter pilots of those robots, eight of them also posing as students. The large robots are called IDOLs and their pilots are called Idolmasters.

In the show, Haruka Amami, initially under confident with herself, passes an audition to be a singing idol and she is sent to Tokyo to start a career in the entertainment. She does not know that the agency that recruited her is actually a front for a big task force which uses robots to save the Earth from falling fragmented pieces of the moon. Yukiho Hagiwara and Iori Minase, who also want to be idols, are also taken by the same task force.

(Source: Wikipedia)