Simoun

I just started watching this series, and I can't put it down.

It's kind of like one of those mech dramas without the long mech fights, but not really...

The story is that a theocratic country has best power technology, helical motors, which have been excavated in their country and are used to power both flying machines and trains. The primary use of this technology, both now and presumably originally, is in offering prayers in the form of patterns drawn with Simoun, their holy airships. The surrounding countries covet the helical motor technology and start war.

In this world, every person is born female. When they come of age, they travel to the Spring and choose their gender. When they do this, they become adults, however, only a child can become a priestess and pilot a Simoun. When war breaks out, the priestesses must use the Simoun as a weapon of war, offering up prayers of destruction to protect their land from the invaders. The government asks the priestess to stay children so that they can fight, but many who don't want to fight or can't stomach war travel to the Spring. Desparate for pilots to fight the war, new recruits aren't from as high a lineage and may not even care about prayers become priestesses, causing inner turmoil in this group and others.

This anime is about how one battle group struggles to become a whole and to save their country.