With Japan, it's not solely (or perhaps even primarily) a matter of not being able to afford kids. Even in Tokyo the fantastic public transport means you can live in one of the more inexpensive wards and still commute basically anywhere in a reasonable amount of time.
People aren't even dating in Japan, though. Marriage rates are way down, people aren't having sex, etc. Even the non-sexual aspects of relationships have been commoditized, with host/hostess bars where you pay to have conversations with people like you would while out on a date, cuddle bars where you pay just to cuddle, etc. Dating video games are huge.
Women being able to more readily progress into senior positions in white collar jobs is a relatively recent occurrence, and getting married/having kids is a good way to end your career, so they're less likely to want to date seriously.