Jorōgumo, the name literally meaning "Spider Whore" in Japanese, is based off of a type of demon from Japanese mythology. The creature is said to be a spider that would take the form of a woman and lure men to her hut. While inside, she would lull them to sleep by playing an instrument. There after, she would bind them in a silk cocoon and drink their blood.
In one chapter, Dōmeki and Watanuki are cleaning out some space at Dōmeki's home. Domeki sees a spider web in a corner of the ceiling and uses a broom to destroy the web. The next day he can not see out of one of his eyes. It is revealed that this spider was a minion of the Jorōgumo and that she was blocking the sight of one of Dōmeki's eyes as a revenge on behalf of her servant.
Yūko tells Watanuki that it was just a web to Watanuki and Dōmeki, but it was a home to that spider. Watanuki then gives his right pupil to Yūko so that Dōmeki can regain sight in his eye.
The Zashiki-Warashi, a supernatural being that has a crush on Watanuki, goes to the Jorōgumo's domain to retrieve Watanuki's eye. However, she becomes trapped in by the Jorōgumo and is unable to escape. The Zashiki-Warashi's servants go to Yūko's shop to ask her to rescue the Zashiki-Warashi in their place as they can not enter the Jorōgumo's domain.
Yūko sends Watanuki with the Pipe Fox Spirit, Mugetsu, to rescue the Zashiki-Warashi from the Jorōgumo. In her house, Watanuki begins to feel faint because he is very sensitive to the spiritual energies present there.
Watanuki arrives where the unconscious Zashiki-Warashi is being held, tangled in one of the Jorōgumo's webs, the Jorōgumo then reveals herself. She threatens him to keep Mugetsu, who is growling at her, under control as he could destroy her home and harm her with his fox fire lest she kill the Zashiki-Warashi. She traps Watanuki in another web and taunts him by showing him the eye he gave in place of Dōmeki's ransom. He shouts that she can keep his eye because it does not mean anything and that he only wants to bring the Zashiki-Warashi out safely.
The Jorōgumo is visibly displeased by this response. She chastises Watanuki saying that he should value himself more as the Zashiki-Warashi values him. He is giving up on retrieving his eye which the Zashiki-Warashi thought was so valuable that she risked her life to see his sight returned to him. That by saying he did not care what happened to him, he was demeaning the Zashiki-Warashi's efforts and affections and that he was hurting those that cared about him by being so careless of himself. She then continues to tell him that his eye is actually very valuable as it contains a high spiritual energy with in it and that if ingested, one could increase their own spiritual power.
She elaborates further that he should fight for the things that he holds important more as she sees no reason to give up the Zashiki-Warashi, either. If she were to likewise devour the Zashiki-Warashi, her life span would increase some significant amount of year. She says that this makes the Zashiki-Warashi valuable to many and that she sees no reason to give up Watanuki's eye or the Zashiki-Warashi.
During her speech, Watanuki has grabbed a shard of broken glass which he then holds to the Jorōgumo's throat. He will be taking the Zashiki-Warashi out of her domain by force and then calls to Mugetsu to set her web aflame. As Fire Fox Spirit's fire does not harm the people it likes, Watanuki and the Zashiki-Warashi are unharmed.
The Jorōgumo applauds his new attitude and his rescue of the Zashiki-Warashi, but goes on to say that she will still be taking his eye and he has failed in retrieving it. She swallows his eye whole and, in a dual panel shot, Watanuki loses the sight of his eye as it is digested by the Jorōgumo. She then vanishes as the Fire Fox Spirit's fire encroaches upon her.
She appears again, many chapter later, after the death Yūko and Watanuki's succession of her as the shop's owner. She returns as a customer requesting Watanuki to find a pearl.
Watanuki uses his strong, spiritual power to enter the dream of a being, that was abused due to its long life span, to retrieve it. The pearl is made of this creature's tears. Watanuki retrieves the pearl from this thing and bequeaths it onto the Jorōgumo.