What should I do regarding health insurance?

Hello everyone,
At the end of next year I will be staying in Japan for six months on a Working Holiday visa.

I want to make sure everything is properly arranged regarding health insurance. Due to legislation in my home country, I am required to keep my native health insurance. At the same time, the visa requires me to enroll in Japan’s National Health Insurance.

From what I understand, Japan’s National Health Insurance does not cover everything, such as permanent disability, liability/damages, or emergency medical repatriation. In the event that something like this were to happen, I would like to be fully covered.

I’d love to hear how others have arranged their insurance in a similar situation. What options are available (I am an EU citizen), and what would you recommend?

Thanks in advance for your advice.