I have a certain health issue which requires regular doctor visits. My daughter was born here three years ago with several complications.
So I have some experience with the US and Japanese systems. Here are some of the differences:
All ambulance rides are free of charge. All hospital fees are set each year by a government panel. So when I need my yearly MRI it costs $150 no matter what hospital I go to. The co-pay is 1/3 of the bill. So my MRI is $50 to me. There are caps on what hospital can charge for extended stays. My wife had to stay in the hospital for a month, C section, then my daughter needed surgery and she was in the hospital for 3 months. When the bill came I was surprised that we only had to pay $600. After you stay in the hospital over a certain number of days, they can't charge for additional days. Healthcare is basically free for children under 15. My individual insurance costs me about $60/month. And, somehow, amazingly, the healthcare is excellent.
The only reason it is so expensive, so convoluted and exasperating in the US is because it has been politicized.