Not sure actually... It seems that XS Games hasn't published anything since March 2007 (The Red Star), while Aksys's first game was published in October 2006, though their next one after that was June 2007. They're probably different companies.
XS Games did publish Castle of Shikigami II on PS2 in the US, though. They kept the actual game name and character names that time, and not only did they leave the story in (unlike Gunbird or Shikigami 1), they actually TRANSLATED it (unlike the endings to Sol Divide, which were text only endings that they just left in Japanese)! It was about as accurate a port as Castle of Shikigami III is, except with a hilariously bad translation and awful voice acting.
Anyway, my point was mostly "it could have been a lot worse", not that the same company released both titles.