|Japanese name:||本郷 唯|
Yui is initially transported to "The Universe of Four Gods" with Miaka, but almost immediately returns to the real world and becomes the one who reads the book in order for events in the world to progress. However, she becomes trapped in the book while trying to help Miaka return to the real world. Afterwards, bandits capture Yui and knock her unconscious. When she regains consciousness, she believes she has been raped and, distraught, attempts to kill herself. Nakago rescues her and convinces her that Miaka is responsible for Yui's misfortunes, leaving Yui unaware that he had saved her before she had been raped. He manipulates Yui into becoming the Priestess of Seiryū, convincing her that it will allow Yui to take revenge on Miaka. She eagerly agrees, swearing to fight Miaka and to take away her lover, Tamahome, whom Yui has become attracted to.
After succeeding in summoning Seiryū, Yui uses her first wish to seal away Suzaku's powers, preventing the god from being summoned and the Celestial Warriors from using their powers. Her second wish is to take Miaka and herself back to their world, hoping to separate Miaka and Tamahome, but Tamahome also arrives in their world with them. Upon learning that Nakago had been using her all along, she has a change of heart and redeems herself by using her third and last wish to disable the seal on Suzaku, allowing Miaka to summon it, but she is absorbed by Seiryū afterwards. After summoning Suzaku, Miaka used her first wish to rescue Yui, and they became friends again.
After the events of the "Universe of the Four Gods", Yui enters a long-term relationship with Tetsuya Kajiwara, a friend of Keisuke Yūki, who fell in love with her while following her journey when reading the book.