Namine is an original character created for the Kingdom Hearts series. She is Kairi's Nobody, created during the events of Kingdom Hearts. She has the ability to change or erase the memories of Sora and those close to him by rearranging and creating new links between them, for which she is referred to as a witch.
Unlike the bold, extroverted, tomboyish Kairi, Namine is shy, introverted, and girlish. However, she does have a playful and mischievous streak as well.
Pluto meets Namine when she appears to spring him and Kairi out of the prison cell of the Castle That Never Was. While Kairi is confused as to who Namine is, Pluto can smell right away that she's the other half of Kairi. As such, Pluto is naturally as fond of her as he is of the Princess of Heart. Even after Kairi and Namine remerge upon escaping the Castle That Never Was, Kairi often lets Namine out of her heart when visiting the kennel, allowing Pluto to play with her.