20 years ago a mecha called Devadasy was discovered in Tibet, and the organization Spirits was created to study and repair it. In the present day, an alien invasion has begun and Spirits is now an organization that uses Devadasy to combat this threat. Two friends, Kei and Naoki, join Spirits to help save mankind and become Devadasy's pilots - but what secrets is Spirits hiding about the Devadasy, fellow pilot Amala, and most importantly, Kei himself?
In the future, a devastating event known as Second Impact has destroyed Tokyo as we know it, giving rise to Tokyo III - a city under siege by mysterious lifeforms known only as Angels. Mankind's only line of defense are the Evangelions, a set man-made machines piloted by a trio of fourteen year-old teenagers, Rei, Shinji, and Asuka. The fate of Japan and the entire world now lie with these three children, though they might not have the power to save the most important thing of all: each other.
Devadasy has the same kind of feel as Neon Genesis Evangelion. Secret organizations with mecha they found, fighting against an extraplanner enemy. Main characters that lose control and have their mech go berserk. Secrets about the mecha and what their actual purpose is.
Devadasy ends up being a light version of Evangelion with a few of its own twists. If you enjoyed one, you might want to check out the other.