Why has the number of cards I own decreased?

Please check in "Obtain Flair" that you have not exchanged cards for Gold Frames, Flair, or Special Shop Tickets, or that you have not given cards to another player through Trade or Share.

Note: Special Shop Tickets can only be exchanged using cards of ☆ rarity or higher.
Note: Exchanging for flair, Trading, or Sharing cards can create a discrepancy between your grand total cards acquired and the number of cards you own as displayed on the "My Cards" screen.

■Steps for checking flair:
Tap My Cards (second button from the left at the bottom of the screen) > card with flair > leftmost button at the top of the screen.

■Steps for checking Trade history:
Tap Social Hub (middle button at the bottom of the screen) > Trade > History.

■Steps for checking Share history:
Tap Social Hub (middle button at the bottom of the screen) > Share > History.