***Beggining of Tsubasa - RESERVoir CHRoNiCLE's plot***
The series begins by introducing childhood friends with quite a strong and close friendship: Syaoran, a young archaeologist who is investigating a ruin within the Kingdom of Clow, and Sakura, princess of the Kingdom of Clow and daughter of the late king Clow Reed. When Sakura visits Syaoran in the ruins, her spirit takes on the form of a pair of ghostly feathered wings that disintegrate to other dimensions.
Desperate,Shaolan is willing to do anything to save Sakura...
************************************************************

I've shortened the Wikipedia's plot to not spoil too much.
If you want to read the manga's don't hesitate. An anime also exist, but personally I was disappointed. By the way, the musics are great ^^
It has to be read with XXXHolic because of some important crossover with this one.

Have a nice hanjie !