When a young girl, Rekka, wakes up from a dream, she finds a ring of light over her head and she is welcomed by a group of girls who had wings on them. Rekka then becomes a member of the Haibane Alliance, the group who protects the town of Guri, enclosed by walls. Why did Rekka become a Haibane? Who were the Haibane? As Rekka continues her life in the peaceful town of Guri, the mystery behind her new friends begin to be revealed.