The Oneamisu sector was a region of space. The Braslota system was located in this sector.
In 2365, the USS Enterprise and the USS Hathaway conducted a Starfleet battle simulation in the Braslota system. (TNG: "Peak Performance", set artwork)
Most of the simulation information consisted of in-joke references to Anime (Japanese animation), including The Wings of Honneamise (aka Oneamisu No Tsubasa) for this specific example.