A distant star system some seven thousand light-years from Federation space, where Q flung the Enterprise-D in 2365 and Starfleet first encountered the Borg.
System J-25 is an unexplored star system far beyond Federation territory. It is the setting of the second-season Next Generation episode Q Who.
In 2365, after Picard refuses Q a place in the crew, Q hurls the Enterprise-D thousands of light-years across the galaxy to prove that humanity is not ready for what lies ahead. Starbase 185, the nearest friendly port, is more than two years away at maximum warp. Scans of the system's sixth planet show that its cities have been scooped from the ground, the same damage seen at outposts along the Neutral Zone.
A Borg cube then arrives, slices a section out of the saucer with the loss of eighteen crew, and pursues the ship relentlessly. Only when Picard admits that he needs help does Q return the Enterprise home.