Hyoton system

The Hyoton System is the capital and the homeworld system of the Xi'an Empire. It has been Xi'an homeworld system since the prehistoric times. The system doesn't appear on the Starmap.

Hyoton I
The position of Hyoton II, III, and IV are mentioned in the lore (as of June 2021), and their enumeration suggests that there is one other planet, closer to the sun.

Tethle'a : Hyoton II
Tethle'a is a habitable planet.

RyiXy'an : Hyoton III
RyiXy'an is the former homeworld of the Xi'an race. It was rendered an uninhabitable smog planet by a Civil War that led to the foundation of the Xi'an Empire.

Ka'ua : Hyoton IV
Ka'ua is the current capital and the home of the Emperor.

Tethām
The planet is only mentioned in the Letter from Gatac Archives. Since his position is described as 'on the edge of Hyoton', it suggests that Tethām is an outer planet of the system.