Are you willing to ship to Japan at all?
If not politely decline his Best Offer.
Then Block him.
If you have no bids, you can Revise your listing to refuse overseas bidders. Remember to remove Calculated or Flat Rate Shipping for overseas as well.
If you are willing to ship to Japan, you still don't have to accept his offer.
Because I will not be able to track the package to get delivery confirmation
That's probably not true. You can -- but the shipping may be very expensive. So what? If an overseas buyer wants it enough, she will pay.
Again, adjust your Calculated Shipping to include a service that does offer Confirmation of Delivery. ExpressPost should be fine.
You can also insure items against loss or damage without going through the postal insurance system. One company that is often mentioned favourably on these boards is shipinsurance. They do one-off insurance for quite reasonable rates.
And of course, both the Japanese Post Office and the Japanese people are known for their efficiency and honestly.