Chihiro sticks her tongue out at her new school at the beginning of her journey.

Chihiro looks through the train window on her way to Zeniba's, demonstrating her internal development since the car scene

Chihiro undergoes tremendous growth throughout the film, beginning as a sullen, apathetic character and ending as a strong and confident heroine by discovering her identity.  Miyazaki expresses this internal development through drawing parallels between characters, scenes, and settings.

The film argues that identity is discovered through perseverance through difficulty.  Towards the beginning of the film, Chihiro needs to find Kamaji, the spirit who runs the boiler of the bathhouse.  In order to reach the boiler room, she has to take a set of stairs attached to the side of the building.  When she finds it, she is obviously nervous, clinging to the wall with anxiety written all over her face and spending an agonizing amount of time timidly lowering herself on each step.  Later, Chihiro must rush to rescue Haku on the top floor of the bathhouse by running across an external pipe to a ladder.  The way that she stands, hugging the wall and facing the danger, calls back to the earlier scene at the stairs, but this time Chihiro does not hesitate or allow her fear to slow her down.  She literally rolls back her sleeves, grits her teeth, and goes for it.  Even when the pipe begins to detach from the wall, Chihiro doesn’t indulge in a scream, staying determined and running despite the peril.

This and other instances exemplify the necessity of determination and perserverance in discovering identity.

Chihiro and No-Face sit side-by-side on the train, underscoring their similarity.

Spirited Away's No-Face remains the film's most cryptic and iconic character, residing in a cultural habitat with the likes of Pikachu and the USS Enterprise.  Even if you haven't seen the film, he probably seems at least a little familiar.

No-Face is a profoundly interesting character as, much like Chihiro, he undergoes tremendous transformation throughout the film, though his is largely a negative experience. When he is first introduced, No-Face is a sort of blank slate: speaking only in faint grunts and, it is implied, only interacting with other spirits after Chihiro shows him compassion.  After he sees bathhouse workers' admiration for a rich customer, No-Face attempts to take his place; hiding in the same tub and luring employees to him with gold. No-Face then eats a worker and takes on the victim's characteristics: his voice, snarky attitude, and froglike legs.  But despite the extensive pampering that he recieves because of his gold, No-Face doesn't get the same devotion from Chihiro who rejects his gifts.  After this rejection, No-Face becomes a true monster, eating two more people and wreaking general havoc in the bathhouse.

The extent of No-Face's monstrosity is a warning of the dangers associated with burying one's inherent self.  No-Face and Chihiro both entered the bathhouse as ostracized figures, but No-Face in bending to societal pressure and adopting a manufactured personality became horrific.  Putting on a false persona of wealthy patron, he gained only fleeting pleasure, and could only achieve his happy ending by rejecting this inauthenticity and learning to accept and develop who he already was, just as Chihiro does.