Rumi

"I'll miss you, Chihiro. Your best friend, Rumi.
 * —Rumi's goodbye card to Chihiro"

Rumi is the best friend of Chihiro Ogino, of whom she had to leave when she and her parents, Akio Ogino and Ichiyūko Ogino moved to a new town. The film starts out with Chihiro sulkily reading Rumi's card aloud as it rests on the bouquet that served as Chihiro's goodbye present. The card is decorated with drawings of flowers and hearts, and what is, presumably, a doodle of Rumi herself.

Trivia
Rumi's name is likely derived from Rumi Hiiragi, who provided Chihiro's voice in the original Japanese version.