Tegami Bachi (or Letter Bees) are couriers that deliver important letters and packages throughout the land of eternal dusk, Amber Ground.
The story revolves around Lag Seeing, a young boy who was born on The Day of Flicker, 12 years ago when the man-made sun went down for unknown reasons. The manga follows his ambition to become a Letter Bee and how he follows the path of his idol Gauche Suede who suddenly went missing one day...