Sakura found those cards and her library. When she opened the book, she took a card and
said: "Windy". Then all the cards shot and dissapear.
The clow cards have 2 guardians: Yue and Kerberos(kero-chan).There are 52 cards in total.
An average card gets sealed by defeating it, but there are some cards than need something
different. One example is the mirror: Sakura needed to say the card's name in order to seal it.
This cards have feeling too. The mirror is in love with Touya.
After Sakura seals every clow card, she has to convert them into sakura cards. The only
difference is that sakura cards are pink and the symbol and the back is different.