It makes no sense that Chugoku is a sigma. Its more an independant world.
It links Kusari with sigmas and taus
Edit:
Something else. Why is the system called 'unknown' still a thing?
First a system called 'unknown' should be categorised as Uncharted by default.
Second it doesnt serve a single function.
Turn it either into an uncharted system or move it to omicrons maybe.