People are mentioning this is due to lack of testing, but if that were the case wouldn’t hospitals be overwhelmed like they have been in Italy and elsewhere?
Testing or no testing if hospitals run out of ventilators for people in need, or out of masks, that would still happen if the disease was spreading like it does elsewhere
Note: that article also lists number of ICU beds per 100000 population, and it seems that it's not that highly correlated. Turkey has the most ICU beds.
I think due to the nature of (generally) exponential growth, no country can be expected to be able to "cover" a true outbreak. However, it's also true that the spike in cases will only happen in a very short period of time so it's not very informative to look at hospital beds if the peak is not there yet.
That said, I would expect Japan to be further on the growth curve compared to other Western countries, so not sure what's going on especially given the limited information.
I have no real data to back this up, but it could also be that there's a lower number of comorbidity across the average population. Or it could be that Japanese have perfected 'social distancing'.
Testing or no testing if hospitals run out of ventilators for people in need, or out of masks, that would still happen if the disease was spreading like it does elsewhere