|Previous Leader(s)||Kazaguma, Kushibi, Hotsuma, Kuva|
|Manga Debut||Chapter 111|
Sei Kingdom (斉国, Sei ōkoku) is the country southwest of the Kouka kingdom. All that is known is that it has a Sei has three kings, Hotsuma, Kushibi and Kazaguma. Kazaguma is the one officially ruling the country, but he holds no real power. After King Soo-Won destroyed Hotsuma and Kushibi's forts to save An Lili, the kings of Sei had no choice but to submit Sei to be Kouka's Vassel State.
Sei is situated on the south western half of a peninsula and shares boarders with Xing (who is east of Sei) and Kouka (which in to the north of Sei). It is surrounded by ocean from two sides and has a strait behind mountainous terrains that draw the line to Xing's territory.
Sei has three kings, Hotsuma, Kushibi and Kazaguma. Kazaguma is the one officially ruling the country, but he holds no real power. The power of the country had belonged to his mother Kuva who ruled along with his uncles Kushibi and Hotsuma. Kuva had the support of the citizens, Hotsuma controlled the military and Kushibi controlled the economy so these three had a balance in power and formed an alliance. However, when Kuva passed away the two uncles decided to aim for the throne.  After King Soo-Won destroyed Hotsuma and Kushibi's forts to save An Lili, the kings of Sei had no choice but to submit Sei to be Kouka's Vassel State. 
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|Tribes||Sky Tribe • Fire Tribe • Water Tribe • Wind Tribe • Earth Tribe|
|Capitals||Kuuto • Saika • Suiko • Fuuga • Chi'Shin|
|Villages||Katan Village • Touka Village • Village of Hakuryuu • Village of Seiryuu • Village of Ryokuryuu|
|Ports||Awa • Shisen • Sensui|
|Miscellaneous||Mist-Shrouded Cape • Wanderer's Market|