Complete at least 10 Tag Missions for Dragon Muscles (Ryu) and 20 Tag Missions for Dead or Alive 5 (Ayane) costumes. Get Master Ninja rank in 5 chapter challenges to get Indigo-Dyed Happi (Momiji) and in 10 challenges to unlock Demon’s Vacation (Rachel) costumes.

Ninja Gaiden 2 has mostly been a big hit for Team Ninja, but it seems that the team's work isn't quite done. It recently confirmed that a big update for the game is planned for mid-February that will add "additional features".

This may not quite be the definitive version, but it's still a gorgeous improvement to an excellent action game.