QUICK BIO
Sakura finds The Wood She also another Clow Card covered in ink. Which she doesn't know what is right away. She left the cards on the table without writing her name on them. While taking her fathers papers to him... When she returns she's in for a surprise. Kero scolds her "A Clow Card will obey your order only after you write your name on it."

SOURCE: Card Captor Sakura