I still really don't get the 'Graduation might as well means the other person died' in Japan.
At my graduation, I was like 'Well... tomorrow at your place as usual?' and next to nothing changed.
I lost contact with literally everyone I went to high school with, within two years of graduation. I can't even find my closer friends on Facebook.
I think it really depends, I went to a prep school for high school with a lot of rich kids, and most everyone went all over the US for college, I went to Pennsylvania, my best friend went to Wisconsin, etc. But not everyone has that situation happen.