Thank you for your question, Yasunori. I will answer for Japan here (which will apply to all countries as well) and at the end I am going to put up links that are for our Amazon UK purchasers.
You can easily order through our site for Japan:

Go first to the BUY page: https://www.nowbysolu.com/product/n-o-w-by-solu/

use the “Add to Button” cart.
Then “Proceed to checkout.”

We charge $35.00USD to Mexico and Canada, $45.00USD shipping to all other countries outside of the USA for the first unit per order. Each additional unit in order is $10.00USD per unit shipping.

Fill out your address, payment on the right side of screen. We will ship out to you immediately.

International buyers are responsible for whatever customs charges/duties are due in their own country at time of receipt.

We WILL be on Amazon Japan this year!

Meanwhile, for European buyers, we are now on Amazon and have listings in several countries. Find those links for N.O.W. here:

UK: https://www.amazon.co.uk/dp/B072KHM8JS
Germany: https://www.amazon.de/dp/B072KHM8JS
France: https://www.amazon.fr/dp/B072KHM8JS
Spain: https://www.amazon.es/dp/B072KHM8JS
Italy: https://www.amazon.it/dp/B072KHM8JS