The Nirellia system, a star system, resided within the Oktos sector. This sector itself existed within the galactic territories referred to as both the Mid Rim and the Slice. This system served as the native habitat of the Nirellian ground-slugs.
The reference book The Essential Atlas, authored by Jason Fry and Daniel Wallace in 2009, marked the initial appearance of the Nirellia system. It was located within grid square Q-11 in the book.