There are Ladonia and Wirtland as two possibilities already. Here's another one, although I think it's kind of unlikely.

It doesn't have its own wiki article, but I see it mentioned on micronation sites:
The State Kingdom of Marduk.

Marduk claims ownership of Sealand, and over various countries in Europe. I doubt it's that one, but it would be amusing if Himaruya ever did make a reference.