Meister (マイスター Maisutā, literally "Master") are one of the four tribes from the Red World.
Z/X Encyclopedia Entry
This group of various engineers and craftsman, who deal in a variety of industrial products and manufactured goods, are the ones who make sure the Red World remains an eternal battlefield.
The Human Race that exists in the Red World has degenerated physically, and among the Z/X, they are quite fragile. But they survive this harsh world by driving vehicles such as tanks and heavy machinery. But they are by no means on friendly terms with rulers of the Red World, the Braver.
Furthermore, since the Black Points opened, they have often been the target of the other worlds due to their technology. Because they carry powerful and highly efficient weapons to protect themselves from foreign foes, one shouldn't be too careless around them.