A girl dreams of falling from the sky and awakens in a strange town, inside the Old Home where the haibane, those of small grey wings and halos, live. She has arrived like they did before her, born from a giant egg which grew from a fallen seed. And as is their custom this new haibane is named after her dream: Rakka, falling. It isn’t long before her wings burst painfully through her skin and the other haibane craft a halo for her, though it doesn’t want to stay put without help.
The home where the haibane live and the nearby town of humans are surrounded by a gigantic wall that is impossible to see over and beyond which it is forbidden to pass.