Card Captor Sakura is about a little girl named Kinomoto Sakura who (duh) catches cards.

Cerberus [or Kero-chan]

Kero-chan's real name is Cerberus. He's the guardian beast of the Clow Book. He was named Kero-chan by Sakura and Tomoyo. Kero-chan was sleeping (for quite a long time ^_^;;) during the time when Sakura found the Clow Book.
He doesn't seem to be too fond of Syaoran-kun. ~_~;; By the way, this is NOT his original form. Although this one IS cuter...^_^;;

Contain Spoilers!!
Leave if you do not want to be spoiled.

Yue

Yue is the true form of Yukito. He remained sleeping inside Yukito until volume 6 in the manga (don't know about the anime since I didn't see him appear thus far ~_~;;). He's to pass judgement on whether Sakura was worthy of being the Card Captor. And if I remember correctly, the reason that Yukito eats a lot was also because of Yue...something about energy. ~_~;;;
Whoo-hoo! Another bishounen! ^_~

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