Tegami bachi (letter bee)

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.

main characters

 * lag seeig
 * zazie
 * connor
 * niche
 * gauche

official site
tv-tokyo.co.jp/anime/tegamibachi