Tegami Bachi

Tegami Bachi takes place in a very strange world known as Amberground. It has no sun but there is a geostationary artificial light source above the capital, which means that it is darker further away from the capital. The capital is a mysterious place that is never seen in the series.

Amberground is mostly a wilderness that is dotted with communities that somehow eek out an existence with so little light. The only communications between the communities is via a hand delivered postal system that is run by the Tegami Bachi (Letter Bees). Unsurprisingly, many people have some animosity toward the capital, and the Letter Bees take the brunt of it as the only public representatives the government. Why the government shields itself behind postmen is another mystery.

The wilderness is a dangerous place inhabited by by powerful bug like monsters. The postmen have a technique which uses their life force, that is able to kill the creatures. The ability depends on a gem stone which is embedded in a weapon that focuses the attack. Why only the Letter Bees have this ability, is never explained.

Each Bee has an companion called a dingo which is usually an animal but not always. The main character, Lag Seeing, has a dingo, Niche, that looks a little girl but seriously is not even close. Niche is described several times as "a child of Maka" but who or what exactly a Maka is, is yet another mystery.

The story revolves around Lag searching for clues about another Bee, Gauche Suede, who has disappeared. Gauche delivered a very young Lag to his grandmother, and is the reason Lag became a Bee. Most of the series develops the characters and background, and we only find what happened to Gauche in the final episode, which actually raises many more questions than it answers. Yes, it's another mystery.

There's a very good reason why the series ends with so many unexplained mysteries. There's a second season. ^_^