I watched the whole thing, and basically have nothing to disagree with. However, I would like to make a few comments.
Yubari, the declining town mentioned early on, is located in a cold, snowy region (Hokkaido). It prospered because of the coal it was producing. Once the coal ran out, it became a typical boom-and-bust mining town, especially one in a harsh climate area. Its population is now the same as it was in 1894.
A few things that the documentary did not touch on:
Older unmarried women seem to be unfamiliar with the concept of dating. For example, if a man asks a female coworker out for a meal, her first response is likely to be "Who else is coming?". During lunch, the female employees at a company will usually sit among themselves. There seems to be an unwritten rule that men and women eat lunch separately from each other.
Many Japanese female university students, while technically adults (half of them, at least), still don't seem to have grown out of the "boys are icky" stage. And a guidebook for new students that I translated recently contained horror stories of dates gone wrong. "He seemed like a nice guy, but he tried to get me to join his cult." "I thought we were going to a restaurant, but he took me to the red-light district instead."
Japanese married couples tend not to sleep in the same bed/futon. And Japanese wives seem to be interested in sex only as a means of producing babies. Once their "baby quota" is met, they will often stop having sex with their husbands, and often even move into a different bedroom. Also, once the babies start coming, the wife/mother will likely devote her full attention to them, and essentially ignore her husband unless she wants him to take the kids off her hands for the weekend. And nearly all of the husband's paycheck goes to mama-san and the kids. So a boy growing up in such a household sees marriage like that and thinks, "Why bother getting married?"
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