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Eriol Hiiragizawa

Eriol is the reincarnation of Clow Reed and thus retains both Clow's memories and magical power. While he initially appears antagonistic, his ultimate goal is to assist Sakura. Despite his appearance, Eriol is not actually twelve as he halted his aging process to get close to Sakura. His actual age is unknown. Eriol's life experience, coupled with his access to Clow Reed's memories, means that he is significantly more knowledgeable and mature than his classmates.

Yue

Yue is the one of two Guardians of the Clow Cards, along with Cerberus. While Cerberus acts as the elector, choosing a candidate to become the next Master of the Clow, Yue is the judge who will test the candidate. Though very little of Yue's critical information is known for certain, it is logical to assume that his blood type is AB, as it is the type listed for his temporary form and is also the type corresponding to his personality according to the Japanese theory of Blood Type Personality (which is used throughout the Cardcaptor Sakura series). Some fans originally believed that because Yue, like many of the powerfully magic characters in the series, doesn't appear to age, that he was immortal, but this theory was shot down by Clow Reed who said in the fourth book of the manga that "every living thing must come to its end", including himself, Yue and Cerberus though they never seem to age or weaken. On the outside he acts very cold and aloof and is much more serious and intimidating than his counterpart, Cerberus.

Cerberus (Kero)

Cerberus is the guardian of the mystical yet dangerous book of Clow cards. He is the guardian of the sun, one of the two duty bound to protect the powerful cards, and opposite of the lunar guardian, Yue. For several decades he was locked away in the book of the Clow, which held the cards upon the death of their previous master, Clow Reed, until a new master appeared to take hold of the cards and their guardians. Cerberus’s character first appears at the beginning of the series when this new master, Sakura Kinomoto, releases him from the book. Once Cerberus is awakened (he was napping on the front cover) and released from the book he discovers the Clow cards have vanished, and appoints Sakura the title of Cardcaptor, and sends her off to retrieve the cards. Cerberus’s major role in the first half of the story is to select the candidate to take up his old master’s footsteps and inherit the Clow Cards, and to aid the candidate in their task of collecting the now awakened cards. Once all of the cards are captured and the Cardcaptor’s name is written upon them, Cerberus’s chosen candidate is then judged on their worthiness to own the cards by the other guardian, Yue.

Tomoyo Daidōji

Tomoyo is the best friend of the series heroine, Sakura Kinomoto (Sakura Avalon in Cardcaptors). When she discovers that Sakura has become the Cardcaptor, she becomes Sakura's primary assistant by designing "battle costumes" and filming all of her magical (and non-magical) endeavours. (The videotaping, however, seems to be more to Tomoyo's personal benefit and enjoyment than it is to Sakura's.) Tomoyo faithfully keeps Sakura's new identity secret and often covers for her in times of need.

Syaoran Li

Syaoran is a distant relative of Clow Reed, the creator of the Clow Cards. As a member of the Li clan of sorcerers from Hong Kong, of which Clow's mother was a member, Syaoran believes that he should be the one to inherit the Clow Cards, not Sakura Kinomoto. He first appears as an antagonist in the story, capturing a few cards for himself in the anime (though none in the manga). As the series progresses, and especially after Sakura is officially deemed the new master of the Cards, Syaoran drops his rivalistic attitude towards her and becomes her ally and friend, eventually falling in love with her. However, Sakura is completely oblivious to these feelings and thinks of him simply as a close friend.