Some Haibane do not remember their properly and are called . These Haibane can be recognized by the black stains that appear on their wings. Fans conjecture that these Haibane committed suicide in their past lives; this would appear to be the case with Reki, as her cocoon dream seems to indicate this. Also supporting this theory is the observation that Rakka, whose name means falling, had a fear of heights. ABe encourages fans to reach their own conclusions. Signs of being sin-bound do not always appear from birth. For example, Rakka's wings became discolored only after her close friend Kuu had taken her Day of Flight and gone over the walls. She managed to restore her wings with the help of a crow that had been following her since she arrived. It's speculated that the crow is the reincarnated form of someone close to her from her previous life.