Ai Imajō is one of three waitresses employed at the Jupiter Café in Tokyo, the other two being Dowager and Donkey.

Eiji Miyake, who frequents Jupiter Café in the novel number9dream, calls her "the girl with the perfect neck" because he initially doesn't know her real name and because he thinks she "has the most beautiful neck in all creation."

Ai Imajō is treated poorly by Dowager and Donkey.

Over the course of the novel, Eiji learns that her real name is Ai Imajō and he befriends her.