Yes, every country uses postage stamps.
Greece
Sweden
Hungary
Germany calls itself Deutchland. Actually the country is spelled Deutschland.
Nihon or Nippon or Nippon-Koku - literally means The State of Japan
nippon
Nippon or Nihon
Switzerland - official name: CH, confoederatio helvetica
Japanese call their country "Nihon" or "Nippon".
The Japanese name for Japan is Nihon, and officially Nippon (nippon-koku, state of Japan).
Romania is the country that marks their stamps posta romano.