Sakura and Syaoran in “Unfinished Business”

Sakura

Hey, Li... Do you know who Yue is?

Syaoran

The other guardian of the Clow Cards... Cerberus, the Beast of the Seal representing the Sun. And Yue, the Judge representing the Moon are the ones Clow Reed created to guard the Clow Cards.

Sakura

A judge? What does he judge?

Syaoran

I don't know... Details about Yue are in none of the magic books that Clow left behind... There is that book where you store the Clow Cards, right? The Golden Beast on its front cover is Cerberus and the Moon on the back cover is Yue.

Sakura

There was no moon on the back cover.

Syaoran

Then... just like Cerberus, Yue has taken a material form as well...