What is this piano music..possibly from a japanese anime movie.?

Question:

I remember this girl in my school playing this song during music class and it was from a japanese movie...POSSIBLY. im not 100% sure. But i moved and im not really close to her so i have no way of asking what it is...
So, the song...was played by piano only and it was a famous song. Really famous that you KNOW you've heard it before if you've watched those japanese anime movies like spirited away and howls moving castle and stuff. So im saying its not any of the songs that are just there to add suspense of something. I'll know it when i hear it but i cant find it...and i obviously dont know the title and totally forgot the tune. fyi, it isnt one summer's day in spirited away and it isnt merry go round of life and it isnt the name of life.
but the thing is...it MIGHT not be from a japanese anime movie. but it sounds like it. it...doesnt sound super complicated...i think it was kinda calming...im not sure...its been 2-3 years since i've heard it.
Can you just list all the REALLY FAMOUS japanese piano music???

Answer:

These composers have contributed film music.
坂本龍一 Ryuichi Sakamoto
久石譲　Joe Hisaishi
冨田勲 Isao Tomita

If you want the tune to be a popular anime song, I'd recommend for example;
http://www.youtube.com/watch?v=asSqrkJIR…

"Merry Christmas, Mr Lawrence" (by R.Sakamoto) is a world-famous song.
For more tunes, seach by those names.