Amberground is locked in darkness. A man-made star casts only a dim light over the land. The pitch-black wilderness is infested with Gaichuu–colossal insects with metal exoskeletons. The Gaichuu make travel between the cities of Amberground extremely dangerous. But thankfully the Letter Bees, a brave corps of messengers, risk their lives in order to keep the hearts of Amberground connected.
The Dead Letter Office Lag’s hero, Gauche Suede, has returned to the Beehive; but not in the way Lag had hoped.While Gauche lies injured and unconscious, two mysterious government operatives show up to take him away, arousing the suspicions of the Beehive staff. What is the Amberground government trying to hide from the Letter Bees?