Apparently abandoned by his mother, orphan
Lag Seeing is taken as a “letter” by “Letter Bee”
Gauche Suede to a town where his aunt raises him. His affection and admiration for Gauche give Lag the ambition to become a Letter Bee himself, carrying mail through the dangerous wasteland between towns on his world. When he becomes a teenager, he makes the trip to the capital to take the examination to become a trainee Letter Bee. En route, he meets the strange, powerful girl-like creature
Niche, who becomes his “dingo,” a Letter Bee’s travelling companion. Lag yearns to find his mother, and discover why she abandoned him, if she did.
With his mother taken away from him and having lost everything, Lag Seeing is now a letter whose delivery has been assigned to Gauche Suede, a Letter Bee. Despite their troubling start, the two of them become friends, leading Lag to realize what his aim in life is: to deliver people’s most important feelings in the form of letters, just as Gauche has done.
In Amberground, the land of eternal twilight, Letter Bees and their dingos – creatures trained to protect them – deliver mail to the general populace. However, unlike normal mail carriers, their job is perilous as they must traverse the country while fighting off the giant armored insects known as Gaichuu. One day, a Letter Bee named Gauche collects his latest delivery: a young boy named Lag Seeing, whose mother was taken under mysterious circumstances to the capital of Akatsuki. As the pair travels together, they strike up a friendship, but when they finally reach their destination Lag and Gauche part ways. Now, several years later, Lag is about to take the exam to become a Letter Bee himself so that he can meet with Gauche again and find out what really happened to his mother all those years ago. But before any of that, he must find himself a dingo…