It is very important to use the correct materials to learn Sumi-e techniques correctly, especially papers and brushes. After years of research, I found a way to buy papers and brushes that have adequate quality and price (transportation included) that you can buy direct from Japan through Amazon Global. You can buy them by clicking the link below. I am so happy that I can share this with you. If it shows up in Japanese, please change the language to English on the right side of the search section above.
Pincel grande: https://amzn.to/34x9gTP
Pincel pequeño: https://amzn.to/3fqdq6q
I live in Spain and buy a lot of products through Amazon Global from Japan and they have excellent service.
Enjoy Sumi-e even more with these recommended materials!