The reason why we feel a nostalgia for indigo dyeing is because it has been a part of our daily lives since ancient times.
Natural indigo has been used for centuries around the world as a dye and has been treasured by many people.
Indigo is extracted from various types of plant fibers, but the Japanese indigo is taken from a plant native to Japan called "Tade", which is famous for producing a particularly deep shade of color.

When "Tade" is fermented, it becomes a dyeing material called "Sukumo". To this "Sukumo" is added "Fusuma powder" (a powder made from the outside of wheat like rice bran), and slaked lime and ash lye, and then we wait about 7 to 10 days for the natural fermentation to occur.
When dyeing cloth or threads, the indigo is taken out and put in the indigo solution many times to make it darker. Once the threads have been soaked in the indigo solution and taken out, each thread is exposed to the air to oxidize, repeating the process over and over again.
In the case of shiborizome (tie-dyed fabric), after soaking the fabric in the indigo solution, spread it out well and allow it to air-dye and oxidize.
In the case of katazome (pattern-dyed fabric), the process is repeated many times, checking the condition of the glue, and if the glue becomes loose, it is dried, replenished, dried, and dipped in the indigo solution.

It may be a task that needs patience rather than difficulty.
The naturally fermented indigo dye has the characteristic that the more it is used, the better the color becomes, and the more it is worn, the softer and more pleasant it becomes to the touch, making it a wonderful dyeing method rooted in daily life.