The People's Republic of Ostania (東人民共和国オスタニア, Osutania) is a large country that borders the east of Westalis. The capital city of Ostania is Berlint.

The currency used in Ostania is dalc (ダルク, daruku), commonly represented as Đ, and pent (ペント, pento) coins. A 100 pent is equivalent to 1 dalc. This currency is also used in Westalis.

The country promotes its open politics and rapidly developing industry to foreign countries, but this is strongly motivated by propaganda. The security organizations openly promote the arrest of those who spread unfavorable information and facts to other countries, and speech is strictly controlled. However, as long as one does not transmit information that is detrimental to the state, the people of the country can live a normal life with a high level of security, and can freely take up jobs and study, depending on their abilities.

In the past, the National Unity Party, a hardliner against Westalis, was the sole leader of the country. However, after the war, the National Unity Party was deposed from the ruling position, and a dovish party is now in charge of the state administration. On the surface, the country seems to be taking a conciliatory approach with Westalis, but there are many citizens who do not seek reconciliation with the Westalis, leading to a situation where it is difficult to predict when their discontent will erupt.

The countries of Ostania and Westalis border each other with Ostania to the east and Westalis to the west, the iron curtain severing the two countries.