When tasked with a final delivery before a coveted promotion, Gauche Suede ventures into the shadowy outskirts of Yodaka, known as the bleakest region of Amberground. To his astonishment, the package turns out to be a frightened young boy named Lag Seeing, deeply scarred by his mother's abduction and destined for his aunt's care. Amidst the perilous presence of Gaichuu in this desolate land, Gauche and Lag embark on a treacherous expedition that kindles a newfound aspiration in Lag to pursue the path of a Letter Bee.