So - on to a few obvious detail differences in 1991:

• Many young women had long straight hair that reached halfway down their backs.  This was most common among single women in their early twenties, but some high school girls also had it.  Now it's practically unheard of.
• Y100 clear plastic umbrellas had yet to make an appearance, so umbrellas were more varied and more interesting when any crowd opened up a sea of them.
• It was right around this time that schoolgirl uniforms first began appearing as mini-skirts, but it was still unusual.  In fact, this is something that was shocking at the time!  You got used to school uniforms for girls always being long, and so the first time you saw a group of schoolgirls in mini-skirt uniforms, it seemed sort of... I hesitate to use the word, but it fits the feeling at the time: outrageous & almost shocking.  (Not that I was distressed by the sight...).
• The vast majority of the ticket gates were still not automated, so you gave your ticket to an actual living human being.  From this point forward though, they steadily installed automated ticket gates and now there are hardly any stations anywhere without the machines.

This was taken in the Oku-tama area of Tokyo, up near the mountains.  It may not look like Tokyo, but it is.  Probably by design, the western part of Tokyo reaches into the mountains, making it easier to lay claim to part of the watershed there.

Lyle (Hiroshi) Saxon
http://www5d.biglobe.ne.jp/~LLLtrs/