Flag of the Navy.

The Navy (海軍, Kaigun) are the World Government's military sea
force, and collectively serve as one of the longest-running antagonists of the series, alongside the Baroque Works, CP9, and Blackbeard Pirates. They are present in all the seas around the world, although they maintain only a slight military presence in the four Blues by establishing branch offices. The focus of the bulk of their assets is on the far more dangerous Grand Line, as their main headquarters is located there. The Navy HQ was located at Navyford, but after the timeskip, it is relocated in the New World.