So in my headcanon Haku keeps his promise and meets Chihiro again. Because you kinda left that one wide open, Miyazaki. Wiiiiiiiiiiiiide open.
Anyway. Back to my headcanon.
So everybody's older! Huzzah!
Chihiro, who is now in high school, actually made some friends, etc, and is now leading a relatively normal life. Of course, she hasn't told anybody about her Spirit World shenanigans: they'd think she was crazy.
...so she only freaks out a little bit when she gets a visit from an old friend.
Here we have Haku being uncharacteristically unhelpful while a panicking Chihiro is desperately trying to shove him into her closet to avoid detection.
For some reason he won't turn human. Or whatever.
I tried my best to stick to the Ghibli style, but, well...

I tried.
Yes. I am aware that I suck at dragons.
Anyway, hope you like it!
Spirited Away etc. belongs to Miyazaki/Studio Ghibli.
In the meantime, feel free
I love the idea of Haku being a bit of a troublemaker in his dragon form. Oh, this made my morning. Thank you for sharing this with us.