Where are they from?

Germany of course. In further depth; Bill and Tom are from Leipzig (and have recently moved to Loitsche, a town near Magdeburg), Gustav and Georg are from Magdeburg.

Why the name?

Why not?

Tokio for something international (almost as if they knew they would be loved world-wide!) - also because the boys would like to go there. Bill recently said his dream would be to play in Tokyo...and Hotel because when touring countries they stay in many different hotels.