Final Fantasy XIII - Save Stations
You can save your game at a Save Station. When you're near one, press X/A
and a menu will appear. Choose the first to save, the second to shop, the
third to upgrade and improve weapons and accessories and the last to go
back to the game. In the shops you can buy various things. As you progress
through the story, more shops will be available, and thus more items.
The upgrade option comes later in the game and is explained after the
walkthrough. Save Stations are available almost every 5-10 minutes of