Every stage is represented by a Battle Card character as the stage avatar. One stage includes three battles. You need to win at least one battle in a stage to unlock the next stage.
a. Three statuses of the stage:
-Locked: A locked stage shows a dim icon.
-Unlocked: On the completion of one battle from the previous stage, the next stage becomes unlocked, and it shows a bright icon.
-Cleared: After winning all three battles in one stage, the stage is now cleared/completed. You can always come back and challenge the same battles without consuming Vitality Point, but you will not be able to earn the rewards again.