The anime starts with an exposition that pretty much tells us nothing about the main hero, except the fact that he is the most wanted and dangerous criminal in the world, just to show the most nice guy possible, and make you wonder what got him that name in the first place. This, as well as the environment that pretty much gives off a feeling of a "wild west" type of show (maybe with a few steampunk elements thrown in), just adds to the enjoyment and interest when you understand how wrong you where, when it turns out to actually be sci-fi, as you start to understand what's really going on and the pieces start coming together.
The only bad things i can say about it is that the colors and animation is a bit outdated, yet it still looks very good non the less. Final verdict- this one, is a must watch for anyone that likes sci fi.
