It is rather curious that the character who is responsible for the romantic quest to the bazaar never actually has a name in this brilliant short story. Yet, if we think about the main conflict of this tale and the way in which Paul's romantic notions and illusions are contrasted with the reality of life which is forcibly imposed upon him at the end of the story, we can see that Mangan's sister is not named because it reinforces how impractical and illusory Paul's dreams and notions were. The story makes it clear that he views this trip to the bazaar as something approaching a knight-errant's quest for his lady:
I imagined that I bore my chalice safely through a throng of foes. Her name sprang to my lips at moments in strange prayers and praises which I myself did not understand.
Clearly, such romantic notions are reinforced by the way in which Mangan's sister is such a half-drawn, undeveloped character. The boy builds so much on actually very little, and the epiphany that he experiences at the end of the tale is made all the more profound because he based so much of his dreams on a character who he knew so little about.
Mangan's sister is the object of the narrator's affection and is unaware of the narrator's infatuation with her. She is associated with the Virgin Mary in the narrator's mind and is the focus of the narrator's attention throughout the story. However, she remains only a minor character, and Joyce does not even reveal her name. In many ways, Joyce's decision to refer to the girl that the narrator is infatuated with as simply "Mangan's sister" reflects her actual influence on that narrator's life after he experiences his epiphany. At the end of the story, the naive narrator realizes that Mangan's sister does not care whether or not he holds true to his promise and that their brief exchange was simply small talk. His infatuation with Mangan's sister is a product of his childish, chimerical thoughts. She essentially becomes irrelevant as the young boy's dreams deflate after he realizes the reality of his situation. Joyce's decision to not name Mangan's sister illustrates the irrelevance of her existence in the narrator's life and illuminates the detached relationship that actually exists between the narrator and the girl.