One of the lesser discussed principles of Japan's national health insurance policy is that it only pays for treatment. That sounds like a pretty broad mandate, but what most people don't realize is that "treatment" presupposes a condition that needs to be remedied. In other words, you have to be sick. If you're not, insurance won't cover it. That's why pregnancy testing and periodic checkups are not covered by insurance, though many local governments provide free cancer screenings and other preventive measures to residents of a certain age.
This principle receives a thorough test in the realm of organ transplants. Last week, the Tokyo Shimbun ran a letter from a 65-year-old woman who said that she wanted to donate one of her kidneys to her brother, who had to receive dialysis treatment at least once a week. Living organ donors have to undergo a series of tests to make sure that the organ they are donating is compatible, and the woman spent one week in an Aichi Prefecture hospital where her kidneys, as well as her overall health situation, was thoroughly scrutinized. Afterward, doctors determined that her kidney was "not functional enough" for transplantation into her brother.