In late June of 2024 I visited the Shiozawa Tsumugi Fabric Museum in Minamiuonuma, Niigata Prefecture. They had an excellent array of Shiozawa Tsumugi, Tokamachi Kasuri, Echigo Jofu, and other fabric and kimono on display and for purchase, as well as educational exhibits on silk farming and the dyeing/weaving process of Shiozawa Tsumugi.
In the studio space on the second floor they offer workshops to try weaving with silk as well as an alcove with books containing innumerable fabric samples of Shiozawa Tsumugi, Echigo Jofu, Hon Shiozawa, and Natsu Shiozawa. The double ikat technique employed in the creation of these fabrics is incredibly fine.
Thank you to the kind man who helped explain some of their methods and products and allowed me to explore the museum! You can check out their website here: https://www.tsumugi-kan.jp/