I'm assuming that Mikawa Ossan is in his 20's or 30's. If you are relatively healthy and not prone to illness then you probably do not need much life insurance. Just enough for your funeral and to keep your wife on her feet (if you are renting) until she is able to fend for herself. Life insurance is basically for the purpose of taking care of your funeral, your family, along with your kids' education, and your mortgage in case of your unexpected death so that your family will not suffer.
Here in the states it is said that one should have at least 5x-10x of one's annual salary in order to take care of your family. The ONLY life insurance one should carry is TERM LIFE Insurance where you pay a set, low amount each month for a certain term like 5, 10, 15 or 20 years and a for specific amount like $250,000, $500,000 or $1 million. The rates will NOT go up either on a term plan.
If you don't pass away after the term, you just renew it, at a higher rate of course, but it is still cheaper in the long run. Under no circumstances should you get an annuity or any other type of life insurance as they are total rip-offs and you will not recoup the amount they say you will no matter how attractive they make it out to be. Just read the fine print and you will see. It is a total waste of money and expensive over the long run compared to term life insurance. Insurance agents (as well as insurance companies) make most of their commissions off of other than term life insurance. Do not be swayed with talk of millions of yen for, if you invested the difference, you would come out way ahead.
As far as medical care goes, I don't know about Japan as I thought kokkumin hoken covered most of your illnesses and hospital stays. At least it did for me when I lived there. Are you talking about supplemental medical insurance for long term care?
Here in the states I am covered for 80% of my hospital stays, surgeries, etc through insurance at my work that my company pays for. In addition they also pay for a life insurance policy of one years salary. Added to that, I also have accidental death and dismemberment insurance for $250,000 that I pay for at about a dollar a week. It's not much I know, but our house is paid for, we have no kids, and we have substantial savings that my wife can life forever on. If that were not the case, I would have at least $750,000 in life insurance to provide for my family's needs. Therefore, neither of us carries any life insurance other than what our companies provide us, which is not much for the average family.
As I am under 60 (the recommended age), I do not carry catastrophic, long term health insurance where I may need to permanently be in a hospital or nursing home that will cover additional expenses when my million or so of regular insurance runs out. That is quite expensive and I will consider it in several years, but not yet.
I hope this helps, but be careful to not be swayed by the sweet talk of other than term life insurance as I'm sure your agent will not even bring it up as there are no yearly commissions in it for them. How do I know this? Because I was sucked into an annuity life insurance package by a neighbor in Japan that was very expensive monthly and I learned later that term life insurance would have been way cheaper.
Additional term life insurance (over and above what your company or the state provides you) is a must for anybody with a family and a mortgage. It is sad at how many people do not have it today. I cannot tell you the number of times, over the years here in the US, where a collection was taken up for the untimely death of a collegue that had no insurance other than the pittance that the company and social security provided, which is usually one years salary or lower and a low monthly payment - hardly enough to even pay one years mortgage and funeral and the family was really in a bind. Do not make that mistake.