Wikipedia
Reichsbürgerbewegung
("Reich Citizens' Movement") is a label for multiple groups and individuals in Germany and elsewhere who assert that the German Reich (or, occasionally, Prussia) continues to exist not in the shape of the present-day Federal Republic of Germany, but in its pre-World War II borders, and that it is governed by a (, Provisional Imperial Government), or (" government in exile"). There are a number of competing s, each claiming to govern all of Germany.
It can be compared to the Sovereign citizen movement in the USA and Canada.