Jiji is Kiki's pet talking cat and closest companion in Kiki's Delivery Service.
Jiji is Kiki's companion as she is training to become a full-fledged witch. One time, he has to pretend to be a stuffed cat for a boy's birthday gift. The real stuffed cat which looked exactly like him, was lost in the forest and Kiki had to go find it. This was during Kiki's first delivery.
Jiji also gets a girlfriend, a white cat named Lily. In the credits, you see that Jiji and Lily had kittens.
In the American version, Jiji is a chatty and sarcastic cat that likes to act proud. In the Japanese version, Jiji is a cautious and cute cat that acts humble and is always ready to help Kiki.
The character of the cat, Jiji, changed significantly. In the Japanese version, Jiji is voiced by a female performer, while in the American version Jiji is performed by Saturday Night Live alumnus Phil Hartman, and also has more of a wisecracking demeanor. In Japanese culture, cats are usually depicted with feminine voices, whereas in American culture their voices are more gender-specific. A number of Hartman's lines exist where Jiji simply says nothing in the original (such as in the scene where Jiji approaches Lili along the top of the wall). Jiji's personality is notably different between the two versions, showing a more cynical and sarcastic attitude in the 1998 English version as opposed to cautious and conscience-like in the original Japanese.
In the original Japanese script, Jiji loses his ability to communicate with Kiki permanently, but in the American version a line is added which implies she is once again able to understand him.Miyazaki has said that Jiji is the immature side of Kiki, and this implies that Kiki, by the end of the original Japanese version, has matured beyond talking to her cat.