Yūko Ichihara runs a shop that grants wishes, visible only to those harboring powerful desires and appearing as an empty lot to others. She demands payment equal to the wish's worth, which could be an object or something abstract like memories or luck. Her shop exists between dimensions, held in place by her soulless magical creations, Maru and Moro.
Known as the Dimension Witch for her ability to traverse worlds and manipulate time-space, she aids interdimensional travelers like Syaoran's group. She provided the Mokona Modoki creatures, created with Clow Reed in anticipation of their journey[citation:]. Her history with Clow Reed is pivotal; his stray wish accidentally froze her time at the moment of her death, extending her existence beyond its natural end. This drew the enmity of Fei Wang Reed, who sought to exploit her situation.
She possesses long, layered black hair reaching her knees and eyes that shift color, typically red, purple, or turquoise. She wears exclusively unique outfits, often pairing kimonos with thematic accessories. Her eccentric behaviors include heavy drinking without impairment, smoking a kiseru, and employing dramatic methods to deliver guidance.
She hires Kimihiro Watanuki as her assistant after he wishes to escape spirit harassment, assigning him domestic and supernatural tasks. Though treating him with sarcasm and mock annoyance, she protects him and facilitates his growth. Their bond deepens as he discerns her concealed concerns about her impending death, leading him to promise to grant her wish. Philosophically, she emphasizes inevitability ("hitsuzen") and self-determination. She refuses to dictate solutions, insisting clients must act sincerely for themselves. For example, she only aids a woman overcoming internet addiction after the woman resolves to quit for her own sake, not others' expectations.
As her frozen time begins to unravel, she expends magic to maintain the shop and aid Syaoran's group. Fatally injured by Fei Wang's interference during a dimensional transfer, she accepts death to atone for her role in the clones Syaoran and Sakura's suffering. Using wish-payments stored in her shop and Clow's residual magic, she rebirths them as humans. Before dying, she appears to Watanuki in a dream, stating her wish is for him to "continue existing." He inherits her shop, retaining his spirit sight to preserve it. Over a century later, he dreams of her again; she implies he could leave but he chooses to keep waiting for her return.
In "Rō Adayume," she appears within Shizuka Dōmeki's memories viewed by Watanuki, reaffirming her lasting influence. Her posthumous presence persists through artifacts like the egg she gave Dōmeki, passed down to his descendants who assist Watanuki.