The Haibane are angel-like creatures that live in a town with walls. Like the human inhabitants of the town, they cannot pass beyond the walls. They hatch from cocoons that grow in abandoned rooms and are named after the dream they have inside of them.
The story begins with the discovery of Rakka’s cocoon by Reki, and while the first four episodes are about Rakka’s exposure to this world, the series is really about Reki, a Haibane who is sin-bound. As long as she remains sin-bound, she cannot gain salvation, which occurs when good Haibane reach their Day of Flight, and travel beyond the walls.
Important to this world are the Haibane Renmei, a religious order who help the Haibane when they are in need. They do not allow the Haibane to speak to them unless given permission, and then the Haibane can only speak to the head priest. Otherwise, they answer “yes” or “no” questions from the priest using bells that the Haibane Renmei attach to their wings (ringing one bell means “yes,” ringing the other means “no”).
The crisis that sets off the main story is the disappearance of Kuu, a young Haibane whose Day of Flight comes at the beginning of winter. Her absence devastates Rakka, who doesn’t understand what the Day of Flight is and why it occurred so soon. Caught in her own guilt, Rakka becomes trapped in the Circle of Sin. As a result, flecks of black begin appearing on her charcoal wings. Reki notices this and goes deep into the woods to grab ingredients needed to treat them. Still, Rakka doesn’t leave the Circle until she discovers a crow at the bottom of a well and remembers the rest of her cocoon dream. The crow was someone she hurt who tried to follow her when she became a Haibane, in order to let her know that she isn’t alone. With help from the crow, who has forgiven her, Rakka is able to escape the Circle of Sin and is no longer sin-bound.
Reki, however, lost the only person who cared about her and is helpless to help herself out of the Circle of Sin. Kumamori, the Haibane who took care of her and another Haibane named “Nemu” when they were younger, left for her Day of Flight before Reki understood what it meant. Just as Rakka needs the crow and the remembrance of someone who cared about her to pull her out of sin, Reki needs the same, yet she is too proud to ask for help. And while Reki is kind to all the Haibane, especially to Rakka, the last few episodes show the darker aspects of her past.
While many anime series follow the same patterns, Haibane Renmei is mostly cliche-free, and deals with sin and salvation in a non-preachy manner. Occasionally it falls into the trap of explaining too much, such as the episode involving the different colored bells. Most of the time, however, the series is content to explain events at its leisure and let the viewer come to their own conclusions. For example, crows are the only creatures allowed to travel past the walls, but it’s never explained why. Nor is the origin of the town explained, or what the Haibane are, or the Haibane Renmei, or where the sin-bound Haibane go after they miss their Day of Flight (other than the high priest saying they stick around but are shunned by all).
Yet it is its treatment of forgiveness, and the salvation we find not just in forgiving others, but in forgiving ourselves and allowing ourselves to be forgiven, that makes the series special. At one point, the high priest gives Rakka a riddle, “The ones who recognize their sin no longer live in sin.” In keeping with the tone of the series, I’ll let you figure that one out for yourselves.