Overstayers by definition are in Japan illegally and thus are criminals in that they have broken the law. Those acknowledged as not having the right to stay are usually not problematic as long as they do not break the law. Nevertheless, the vast majority are not enrolled in national health insurance. When admitted to hospitals in Japan, they often have no means to pay. Often taxes on earned income are not paid either if they are employed "under the radar."
Two overstayers recently were admitted to a hospital in Chiba Prefecture for serious medical conditions that necessitated surgery. The combined bills exceeded ¥14 million and they paid with only a smile. These are not isolated cases; this behavior is repeated in many, many other hospitals here. Emergency care cannot be denied by hospitals. One solution is for the Justice Ministry — which allowed 10,000 illegal foreigners to remain in Japan annually from 2003 to 2008! — to further cover these people under national health insurance or require their participation as a prerequisite to being allowed to overstay.
Japan's hospitals are in grave financial danger today, and adding this financial burden is an excessive strain. The amount of uncompensated health care provided to overstayers is a multibillion yen loss in revenue to Japan's hospitals. The simplistic view that Japan must show a human face to such immigrants is naive.