Yûko Ichihara, the Dimension Witch, runs a shop that grants wishes only in exchange for something of equivalent value, insisting nothing happens by coincidence and all actions require payment. She exists outside time's normal flow, accidentally frozen by Clow Reed to halt her impending death caused by Fei Wong Reed's spacetime meddling. This temporal suspension lets her manipulate events across dimensions while awaiting her destined end.

She collaborates with Clow Reed to create the twin Mokona Modoki creatures, designed to enable interdimensional travel and thwart Fei Wong's schemes. White Mokona accompanies the protagonists; Black Mokona stays in her shop. Yûko orchestrates the formation of the main group through their wishes: Syaoran gains dimensional travel to retrieve Sakura's feathers but pays with Sakura's memories of him; Kurogane receives the means to return home but surrenders his sword; Fai D. Flowright obtains freedom from his world but forfeits his magic-suppressing tattoo.

Her involvement extends beyond transactions. She foresees and influences the group's journey, knowing they are pawns in Fei Wong's plan to use Sakura's feathers for multiversal control. When Fei Wong revives her to prove superiority over Clow Reed, she uses her restored existence as payment to reincarnate the cloned Syaoran and Sakura as normal humans, correcting their exploitation as creations. This act consumes her life, fulfilling her suspended fate.

Posthumously, her legacy endures through Kimihiro Watanuki, her former assistant who inherits her shop and role. Watanuki maintains the shop for over a century, upholding her principles while awaiting her potential return, reflecting her lasting influence on cosmic balance. Her philosophy of equivalent exchange and inevitability remains a guiding force across dimensions.