Mondo will be able to acquire Moon Crystals as he assassinates his targets in the game, which can be gotten in a variety of ways, such as being hidden in objects or from enemies after performing the Final Judgement finisher, Enforcement Kill. These Moon Crystals can be used to upgrade and learn new skills for Mondo. They are divided into three separate categories:
- Attack Skills - Skills that give Mondo more attacks.
- Sub Weapon Skills - Skills that enhance Mondo's sub weapons.
- Special Skills - Skills that enhance GEKKOU or Mondo's special abilities.
