There is no definitive answer to this question as it largely depends on how homelessness is defined and measured. However, based on available data, it appears that Japan has one of the lowest rates of homelessness among developed countries.
According to a report from the United Nations Human Rights Council, an estimated 0.2% of the Japanese population lives in "severe housing deprivation," which is defined as lacking three or more of the following conditions: access to safe water, adequate sanitation facilities, durable housing, sufficient living space, and secure tenure. This is significantly lower than the 2-3% rate of severe housing deprivation found in other developed countries such as Canada, France, and the United States.
There are a number of factors that likely contribute to Japan's low rate of homelessness. For one thing, the country has a relatively strong social safety net that provides financial assistance to those who are struggling to make ends meet. Additionally, there is a strong culture of family support and communal living in Japan; many people live with their parents or other relatives even into adulthood instead of striking out on their own. This can help prevent individuals from becoming homeless if they experience financial difficulties since they have somewhere to fall back on.
It should be noted that some experts believe that Japan's low rate of homelessness may be partially due to underreporting; because there is such a stigma attached to being homeless in Japanese society, many people may be reluctant to admit that they don't have a permanent place to live. Nevertheless, even if this is true, it seems clear that Japan has much lower rates of homelessness than most other developed countries