The Nepleslian Empire was founded in YE 28. Nepleslia is the rebirth of a very old empire, once the core of civilization. For 28 years, the Ketsurui Clan has forcibly ruled the stars under the banner of Yamatai, primarily through military might. When the Uesureyan Empire split into factions for the last time, the small faction that colonized planet Geshrintall (Planet Yamatai) eventually gained control of the larger faction, boosting its own numbers immensely through the use of advanced genetics. The result was the Yamatai Star Empire. Now, the old faction that has been suppressed, founded on the planets Damasica (now Fenyar), Rok'Veru, and lastly at Nepleslia, is re-emerging with its traditional values and culture, which focus strongly on individual freedoms and the pursuit of luxury.
The best place to learn more about the NSE is in the article on Nepleslians.