
Tsubasa "crosses over" with xxxHOLIC, and as I love that series, I thought I'd better start this one, because as each successive installment of xxxHOLIC is published, I find myself becoming more confused about what is going on.
Volume 1 opens with Sakura, who is a princess in this dimension, welcoming back her childhood friend Syaoran, who is an archaeologist. She is clearly head over heels for him, but her big brother disapproves of her her feelings for him. Syaoran loves her, too, but he seems to feel she is far our of his league. That night Sakura has a vision that leads her to the archaeological dig, and when she gets there and sees a symbol from her dream, she somehow unleashes a powerful force that leaves her unconscious. The king's adviser tells Syaoran that all of Sakura's memories have disappeared. Syaoran vows to help her, and they are sent to another world to find the space and time witch (Yuko from xxxHOLIC), who might be able to help them.
Syaoran and the unconscious Sakura's arrival is the point at which this manga crosses over with xxxHOLIC - that same scene is in that manga, as well. It is an interesting device to connect the series at certain

Syaoran is paired up with two other characters from other dimensions: Kurogame, a grumpy warrior who has been exiled by the ruler of his kingdom so that he might learn compassion (which seems unlikely at this point) and Fay D. Flourite, a mage who has fled his home world for his own reasons. Each must pay a price to Yuko for the ability to move among the dimensions, but Syaoran's price is definitely the steepest. Still, he loves Sakura and pays without hesitation. Yuko then gives them Mokona, a cute little critter with the power to transport them from one dimension to another, and off they go to their first world in search of Syaoran's missing memories.
The second volume in this series is about their adventures on the first world, which is similar to Japan but has one main difference: residents of this land possess a kudan, a sort of magical spirit that resides within them. Depending on their strength, this spirit manifests as a more or less powerful creature - a dragon, perhaps, or an ele

This is a gripping series that has many intriguing and complex elements that make me very curious to see what will happen next. The characters have just been introduced, but already I am interested to watch as facets of their personalities and pasts are unveiled, as it seems there is more to them than meets the eye.
I find it fascinating the way in which this group of mangaka work together to create their various projects. According to Wikipedia, "each member of Clamp has a role different from their other projects as opposed to retaining set roles. For Tsubasa: Reservoir Chronicle, Mokona draws the main characters whereas Tsubaki Nekoi and Satsuki Igarashi draw the side characters and backgrounds; Nanase Ohkawa is the sole person in charge of the storyline and not even the other members of Clamp know how the plot will unfold."
If you are new to manga and are thinking of discovering what all the fuss is about, this series (read along with xxxHOLIC) would be a good place to start if you enjoy sinking your teeth into something complex and fantastical. If you'd like a simpler, introduction, I'd recommend something more straightforward like Dramacon, Yotsuba, or Miki Falls. These are my first books read for the Japanese Literature Challenge, and I'm looking forward to reading the rest of this exciting series.
Tsubasa, Volume 1 by CLAMP (Del Rey, 2004)
Tsubasa, Volume 2 by CLAMP (Del Rey, 2004)