Lost hours

The lost hours are a concept in Lightning Returns: Final Fantasy XIII. Prior to the Chaos being released, days consisted of thirteen hours before and after noon, for a total of 26 hours. After the event, the thirteenth hours were lost, leaving the world with 24 hour days.

If Lightning collects sufficient Eradia from sidequests, the two lost hours from each of the first twelve days are recovered, and form the Extra Day.