Chihiro Ogino is the 10-year old protagonist of the movie. Chihiro is in the process of moving to a new town when her family stumbles upon the entrance to the spirit world.
During her adventure she matures from a whiny, self-centered, and pessimistic child to a hard-working, responsible, optimistic young girl who has learned to care for others. She is renamed "Sen" (千, sen?, lit. "a thousand") by the proprietor of the bathhouse, Yubaba. In Japanese orthography, "Sen" is an alternative pronunciation of "Chi", the first kanji in her name "Chihiro", which roughly translates as "a thousand fathoms". The movie ends with Chihiro retaining her new inner strength.
It is implied that someday she will meet Haku again. It seems that Chihiro might have fallen in love with Haku, but she did not admit it verbally to Haku by the end of film.