The local train bound for Yamakawa bucked and buckled down the coast, jouncing us until our teeth rattled, and Yamakawa was so dinky we had to walk across the train tracks to exit the station. The taxi took us through a confusing rabbit warren of streets and, after asking directions several times, we finally alighted in front of Sakai Shoten, a producer of katsuobushi, (fermented and dried, smoked skipjack tuna that is finely shaved for eating).

The word katsuobushi is often assumed to mean just the shaved flakes sold as the final product, but it is actually the name of the whole smoke-dried skipjack tuna. The shavings can also be called katsuobushi, but the correct word is kezuribushi.

The first thing Hiroaki Sakai asked me was, “Did you know that 90 percent of packaged katsuobushi has merely been smoked but never fermented and sun-dried?” No, I did not. My world turned around that day, and I am back to shaving our katsuobushi as I need it. No more pre-shaved bags.

Sakai is the third-generation katsuobushi producer in his family, which, along with most of the katsuobushi producers in this area, relocated from Kochi Prefecture at the turn of the 20th century. While there are currently 26 companies producing katsuobushi around Yamakawa, of the 50 families that migrated to Kagoshima Prefecture (coming for the busy port), only 8 remain. This is due to the tough job of producing hongare katsuobushi, which is dusted with mold and aged for six months in the traditional method; the proliferation of cheaper production techniques; or having no offspring to carry on the family business.

Despite this drastic drop in numbers of producers, yields have increased, thanks to a demand for arabushi (shavings from the cheaper smoked-only 99.9 percent to which Sakai refers) in instant and processed foods. Sakai left Yamakawa and spent 10 years living and working in Tokyo after university, but eventually decided to return to his roots, and if he had not come back, the company would have died.

The Sakai family produces katsuobushi from two kinds of skipjack tuna: those caught in Japanese waters during the season (spring to fall) and those caught all year long in far waters near the equator. All fish is frozen on-ship and hoisted by helicopters for delivery at wholesale markets at the docks. Sakai Shoten thaws the frozen fish in bubbling cold water overnight, circulating air through the water to aid in an even thaw.

Once thawed, the fish is cut down into four triangular-shaped fillets, which are simmered for two to three hours in baskets in a shallow tank before deboning. The 1 percent of fish designated to be molded and dried for hongare is also smoothed with mashed skipjack tuna meat to prettify the shape and to hide the bone striations.

The rest gets placed in the smoker as is. The smoker is a three-story-high chimney-like room, which holds eight levels of trays. The fillets remain in the smoker for 20 to 30 days and are rotated up as new trays are introduced. The trays are well marked for provenance before being slid into the smoking chamber and shut behind mottled copper doors etched with scratchings from the past.

The pieces that were smeared with fish paste undergo one more step before being fermented. Seventy-something Isamu Matsuue has spent over 60 years of his life working with katsuobushi, and he is the last artisan in the local area skilled at shaving the fish by hand. The special tools, shaped to follow the crevices of the fillet, are no longer being fashioned, so this ancient art may die with Matsuue.

After each piece of katsuobushi passes through Matsuue’s experienced hands, they are set on trays and sprayed with Aspergillus glaucus, a natural mold spore akin to kōji (Aspergillus oryzae). The katsuobushi develops a dusting of greenish-blue mold that will eventually transform into dusky brown. It is held in the 29-degree mold room at 90 percent humidity for 20- to 30-day cycles before being hauled out into the sunlight. The drying process takes six months and yields hongare katusobushi with only 15 percent residual moisture. Using it to make dashi results in a clear, subtly nuanced broth.

After the tour, Sakai ushered us into a small room off of the main building, where visitors are received. We perched on sofas in anticipation as his father swiped a whole dried fillet across the family’s red lacquer kezuriki (katsuobushi shaving box). In the time it would take me to shave a couple of handfuls, the father had shaved a pile that filled the hopper of the shaving drawer. He handed the box around and urged us to take a taste. Not wanting to be greedy, I pinched up a moderate amount but was admonished by Sakai to grab a fistful and jam the whole lot in my mouth to get the full effect of the smoky shavings. Sakai’s wife set a few black lacquer bowls on the table and his father heaped a handful of katsuobushi into each one. After adding a dollop of miso and a lashing of organic tea, his wife handed us each a bowl. “Cha-bushi,” she smiled. “We eat it when there is no time to make miso soup.”

Sated from our bowl of cha-bushi and laden down with katsuobushi purchases, we headed back to Yamakawa Station.

Sakai Shoten: 6146 Fukumoto, Yamakawa, Ibusuki, Kagoshima Prefecture; 0993-34-0070; www.katsuobushiou.com. Nancy Singleton Hachisu is the author of “Japanese Farm Food.” A Stanford graduate, she is married to a Japanese organic farmer in rural Saitama.

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