Japan's replacement rate is now ~1.36. But in western media, it's Japan that often leads on stories like this, over...
Korea: 0.78 (!)
Taiwan: ~1.22
China: ~1.18
One difference is that Japan's older cohort is already there, and that while the problem in those other countries is impendingly more serious, it is a little further off. (depending on which country one might be talking about)
However, Japan is also the most developed of these four, which is an advantage when dealing with situation. Better to encounter this with a certain amount of development already 'in hand', than to reach it without that. Korea and Taiwan are at least comparatively well developed and will probably be better able to cope, but I have little hope for China--by the 2030s China will have some difficulties, enough that the present and coming situation in Japan will look like a cakewalk.
And tho the stereotype is that Japan is very closed to immigration, and I would agree that the present level is inadequate, those other countries have even larger obstacles to immigration--and permanent residence, even naturalization. They might be baby steps, but at least some steps are being taken. I mean, foreigners do retire and stay in Japan, check on how many comparable folks choose to retire in Korea. Or China?!?!? Tho it's not policy, that is an indicator of how friendly each place is to immigrants.
Eg, one common point of discussion among english teachers is that 'you can save more in Korea." Yes, you can, but your employer there literally "owns" your visa, while in Japan your visa is very much not dependent on your workplace. Housing (due to key money, etc) is unaffordable in Korea, which is why most if not many jobs supply a free apartment. OTOH, in Japan any number of foreigners have bought their own houses/condos, can get housing loans, and so on.