Lost Galaxy

Lost Galaxy (ロストギャラクシー) is a location. It is comprised of dead stars and memories.

Plot (Galaxy)
This area is first accessible after clearing the game. Once you board the Galaxy Nauts Gou, Pixie is seen setting a course to Lost Galaxy, and almost gets caught by Kabata Shizune. According to Shizune, this place shouldn't exist, as it isn't even listed on the map.

Hoshi no Nakigara
As you go down each level of Lost Galaxy, the surroundings shows a fragment of Sarjes or Acrous memories. Once you get to the bottom, the pit will activate, allowing you to go to a memory reconstruction of Kiel or Acrous' Spaceship.

Uchuu no Hate
Once you connect both games after defeating Big Bang (team) and Supernova (team), the sealed door at the top opens, allowing you to access the area known as Uchuu no Hate, where a soccer field and Space Rankers are located.