The union says the island's production of kimono silk has similarly plunged, from enough to make 284,278 kimonos during the height of the postwar boom in 1972, to enough for just 5,340 kimonos last year.
Amami Oshima has fallen harder than most of Japan's famous kimono production centers, dragged down by a complex web of wholesalers, dealers and specialized retailers who distribute and sell the island's kimonos. While this antiquated system once benefited the remote southern island near Okinawa by spreading its kimonos to the rest of Japan, islanders say it has now become a burden, keeping the kimonos prohibitively expensive while driving down wages.
Yet the old ways have proven hard to discard, despite a growing sense of crisis. Many fret that there will soon be too few islanders left with the skills to sustain each of the 30 separate steps needed to produce one of the kimonos.
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"If we lose one link in the chain, we lose our ability to make kimonos," said Mr. Kanai, 56, who owns a dirt-floored wooden workshop where silk is dyed in bubbling iron cauldrons and then hung from the ceiling to dry. "If we cannot make kimonos any more, what will be left here?"
Mr. Kanai says the mud-dyeing process alone takes more than a month, as the silk is first colored a burgundy hue with natural dye made from the pulp of a local plum tree. Getting the right shade of red requires repeating the cycle of staining and drying the silk 30 times, he said. Only then is the silk ready to be immersed in the black mud, whose iron reacts with tannins in the tree dye to create the coveted dark brown color.
That is not the most elaborate step. Even before the silk arrives at Mr. Kanai's workshop, it is first woven into a temporary fabric as part of a unique method that the islanders have devised for creating minutely detailed patterns.
After this temporary fabric has been mud-dyed, it is unraveled back into its original silk threads. Each colored thread now has thousands of tiny white stripes where it overlapped with another thread, blocking the mud from touching it at that point.
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As the threads are rewoven into new fabric by nimble-fingered island women, they slowly reveal perfectly formed patterns, ranging from starkly minimalist shapes to elaborate scenes of bamboo groves and flying storks.
"The weaver has a tremendous responsibility," said Mifuko Iwasaki, 70, who has been teaching young islanders how to weave these perfectly aligned patterns on hand looms for 35 years. "If we make a mistake, we undo all the hard work of those who spent so much timing preparing this thread."
Ms. Iwasaki says that when she began teaching her yearlong classes, she typically had 40 students, who were drawn by the fact that weaving offered higher wages than fishing, farming and logging, the island's other industries at the time.
These days, she says she is lucky to get more than two or three students, because weaving no longer pays as well. The myriad of middlemen in the cumbersome distribution system each take a cut, making it hard to reduce prices at the same rate as other items in deflationary Japan. Worse, the brunt of what price cuts have been made inevitably falls on the island's dyers and weavers. As a result, while a new Oshima kimono can still cost $3,000 to $6,000 in Tokyo, weavers say they are lucky to get more than $400 for a month's exacting work. Other craftsmen in the production process get even less.
Nonetheless, islanders say they are reluctant to bypass the antiquated distribution system, saying they feel bound by generations-old obligations and a fear of change. This makes them a microcosm of Japan as a whole, which has been slow to give up its outdated postwar economic model despite years of stagnation.
"It is ironic that we can no longer make ends meet producing something so expensive," said Shigehiko Furuta, 67, who uses colored pens and graph paper to design the minutely detailed patterns.
Shinichiro Yamada, 83, the head of the producers' union, said the island's ornately woven patterns have their roots in the colorful culture of the Kingdom of the Ryukyus, centered in current-day Okinawa. They ruled Amami Oshima until the early 17th century, when the island was conquered by Japanese samurai, who claimed the island's kimonos as tribute.
Mud-dyeing started when disobedient islanders buried kimonos in the ground to hide them, only to discover on digging them up again that the fabrics had turned a beautiful dark color, said Mr. Kanai, who owns the mud-dyeing workshop.
His son, Yukihito, now uses those same centuries-old dyeing techniques to color new types of items, including T-shirts, jeans and even guitar bodies. He is experimenting with selling these over the Internet, to avoid the onerous distribution system.
"We need to become more like artisans in Europe or artists in New York," said the younger Mr. Kanai, 35, who said he is one of the few "young successors" in the island's kimono industry. "Even traditions have to evolve."