xxxHolic & Tsubasa Fanclub

The series' protagonist, Kimihiro Watanuki, is a high school student who is continually plagued by supernatural monsters (youkai) and spirits which are magically attracted to him. The creatures are invisible to all but him, and as a result he feels extremely burdened by them. When he quite literally stumbles into a shop that grants wishes, his life changes drastically.

Within the shop is the seductively beautiful Yūko Ichihara, a witch of many names and esoteric renown. The seemingly all-knowing witch soon gets down to business: she offers to grant Watanuki's wish to be rid of his ability to see spirits. However, a price equal to the power required to grant the wish must be paid. Yūko discovers that Watanuki is very skilled with his hands and a hard worker. As a result, Watanuki soon finds himself forced to perform housework and odd jobs for Yūko until he has done enough work for his wish to be granted.

Shortly afterwards, other characters become involved with Watanuki's position, including his love interest, Himawari Kunogi, and his "rival", Shizuka Dōmeki. The three become increasingly "friendlier", despite the amount of times Watanuki gets annoyed with Dōmeki's unflappable attitude.

Another recurring theme in the manga storyline is that Watanuki's growth and change will be because of his experiences of meeting one person. Yūko, according to a fortune teller in Volume 2, is the one that will change Watanuki. However, it's implied that he will be linked to both Yūko and Dōmeki and that all their connections were foreseen.

Sakura is the princess of Clow Country, which is ruled by her older brother, King Tōya. Her childhood friend Syaoran is a young archaeologist. Sakura is revealed to have strange powers when she has a vision of a mysterious symbol and places she has never seen. Meanwhile, Syaoran discovers the same symbol at the ruins he is excavating. He sees Sakura standing on the symbol on the ground. Ghostly wings appear on her back and a mysterious force begins to pull her into the walls of the ruins. Syaoran rescues her in time, but her wings are scattered across dimensions. The High Priest of Clow Country, Yukito, immediately realizes that Sakura's "wings" were the manifestation of her soul and memories; without them, she will die. In order to save Sakura, Syaoran must journey to retrieve her wings' feathers, the fragments of her memories.

Yukito sends Syaoran and the unconscious Sakura to the Dimensional Witch, Yūko, who is one of the main characters in xxxHolic. There he meets Kurogane, a rough-mannered ninja banished from his world by Princess Tomoyo, and Fay D. Flourite, a magician who fled his world to avoid King Ashura. Each of them must pay with what he values most in order to gain the power to cross dimensions. For Kurogane, it is his sword Ginryū, and for Fay, it is the symbols on his back which regulates his control of his magic. (Fay later reveals that he still possesses magic, but has sworn not to use it without the tattoo on his back.) Syaoran, on the other hand, must pay with his relationship with Sakura: even if he is able to retrieve all of her memories, she will never remember anything about him or their relationship. (This sacrifice also pays Sakura's "toll" to Yūko, because what Sakura values most are her memories of and with Syaoran.) Only when the three agree to her terms does Yūko present them with the power to cross dimensions; a white creature named Mokona Modoki.

While traversing through worlds to find Sakura's feathers, the four travelers and Mokona are forced to overcome many dangers and opponents, some of whom are figures from Syaoran's past who wish to collect Sakura's feathers for their own reasons as they are seen to be objects that hold great power.

Note that because of the crossover characters with xxxHolic, some of the plot points of the two manga occasionally intertwine with each other.