As Genki Takahashi and I drove down the Kyushu Expressway, I was reminded of Napa Valley. As in Napa, the highways are lined with fields growing the local specialty in perfectly manicured rows. But the crop here isn't grapes: it's tea.

Also, you almost never see Tanuki Crossing signs in California.

We were on our way to the town of Kirishima to visit Takahashi's employer, Nishi Seicha, a family business founded in 1954. "Kirishima" is Japanese for "misty island," but it's actually a misty mountain. The shade from the mist is said to produce exceptionally sweet and flavorful tea. As we drove into the mountains, I tried not to hum Led Zeppelin's "Misty Mountain Hop" too loudly.

Kirishima is inaka. The countryside. The sticks. I was here for one reason: I love Japanese green tea. Tea grown in Kagoshima produces exquisite sencha (the most common brewed tea in Japan) as well as small, precious harvests that become matcha, the bittersweet powdered tea that belongs to a class of its own.

Matcha is used in tea ceremonies, as a flavoring in drinks and desserts, and for general consumption as a sweet, frothy brew, whipped with a bamboo whisk and served in a large ceramic bowl with no handle. Good matcha is emerald-green, smooth-drinking, and highly caffeinated. Unlike brewed tea, there are no spent leaves to discard after making matcha: you drink the entire leaf.

And I was on my way to see how it's made.

Kirishima is located in Kagoshima prefecture on the island of Kyushu at the southern tip of Japan. Kagoshima is Japan's second-largest tea growing area and the source of Nishi Seicha's tea leaves. The region's most famous son is is Saigō Takamori, the samurai who led an ill-fated revolt against the post-Shogun government in the 19th century. Takamori is known equally for his military exploits and his fireplug appearance: basically, he was the Japanese Danny DeVito.

"Our company president looks a lot like Takamori," said Takahashi.

"Do you say that to his face?" I asked.

"Yeah, all the time."

Later I learned that Kagoshimans compare each other to Takamori all the time, with no malice intended. Which doesn't mean it's okay to do it if you're not Kagoshiman. So if you happen to see a picture of Nishi Seicha's president, do not think of Danny DeVito.

Into the Mountain

My guide, Genki Takahashi—"I'm the only one at the office who speaks English"—took me to the Nishi Seicha company, where he works swing shifts processing tea into matcha.

We arrived at the factory and met up with Toshimi Nishi, the company's president and grandson of its founder, and headed for the tea fields.

Yes, Nishi is the name of both the company and its president. For an attempt at clarity, I'll refer to the company as Nishi Seicha and the president as Toshimi Nishi. This will probably make sense until we meet the president's brother.

Nishi Seicha is a middleman: they take in raw tea leaves and turn them into nearly-finished tea (aracha). Buyers finish drying and blending the tea and put their own brand name on it. The company grows much of its own tea leaves, but also buys leaves from a cooperative. Nearly all of the tea they make is certified organic.

I've drunk many pots of Kirishima tea, and now I was surrounded by enough of it to brew a lake.

Genki Takahashi explained how the farmers produce organic compost to nourish the tea bushes. We spent a lot of time standing next to a compost heap. "We fertilize the fields with organic matter," said Takahashi.

"He means shit," said Toshimi Nishi. (This was one of the only times he spoke English all day.)

I asked if I could taste a leaf. "Go ahead," said Toshimi Nishi. I pulled one off and stuffed it into my mouth. It was tough and fibrous and tasted like, well, a leaf. How does anyone taste this and decide it'll make good tea?

Toshimi Nishi can. He's more like a chef than a corporate suit. He's the man in charge, but he has an encyclopedic knowledge of tea. And he can learn a lot by tasting a raw leaf: the variety of tea bush, the quality, the time of year. Spring-harvested tea is considered higher quality than late-season tea. It was now July, hot and humid even in the mountains. Specialized tractors with spindly legs and deadly blades on the underside stood by, ready to give the rows of tea a haircut during the next harvest.

We got back in the car and headed for the factory. "Do people at the factory drink tea all day?" I asked Takahashi.

"Nah, they mostly drink coffee."

We gathered with other employees in an outbuilding adjacent to the factory and sat down to a lunch of eel on rice with sides of simmered kabocha squash, potato salad, cold silken tofu, and miso soup. Then Genki and I headed into to the factory proper. "We're making matcha today," he said.

I was excited to see matcha-making, because I'd heard that the tea leaves were ground to a fine powder in massive electric stone grinders.

Takahashi laughed. "We don't do that here," he said. Nishi Seicha produces tencha, the leaves that are processed into matcha. Whatever company buys the leaves from Nishi will run them through its own stone grinders—in small batches, as matcha gets stale quickly. Processing and grinding the leaves in separate steps keeps the tea fresh.

On the Factory Floor

Hiroki Nishi, the president's younger brother, was overseeing the tencha line. (I'm going to call Hiroki by his first name because, well, come on.) Tea leaves arrive at Nishi Seicha's loading dock in shipping containers, about two metric tons (2000 kg) of tea leaf per day. It takes six kilograms of fresh leaf to produce one kilogram of finished tea. A cup of matcha requires one gram of matcha powder, so each day's production is equivalent to over 330,000 cups of matcha, enough to serve a cup to every citizen of St. Louis. From the container, the leaves go into a washing machine, not so different from a clothes washer.

Then they spin dry.

Next comes the step that makes Japanese tea unique: steaming. The leaves go into a rotary steamer for 10 to 15 seconds. Steam gently cooks the leaves just enough to stop oxidation and fix them at a nice green color, without adding any dark, roasted "cooked" flavors.

After steaming comes the most fiddly part of the production process: drying. The leaves go through several rounds of drying, and the retailer will dry the leaves even further before selling them to consumers. The drying process makes the leaves shelf-stable—wet leaves rot—but it also has a major influence on the tea's flavor.

The particular sequence of drying times and temperatures is thus a key component of the tea maker's art, though few agree on first principles. Takahashi began to explain the multi-step process to me. The leaves undergo five high-heat cycles in large tumble dryers.

I had a hard time paying attention, however, because the ambient air temperature near the drying machines is about 150°F. Are you a charismatic preacher who wants to introduce your flock to the concept of fiery torment? I've got just the place.

Just before I lost consciousness, we headed over to the winnowing machine, which uses a vibrating conveyor belt to separate leaves from stems, using the same principle by which all the raisins fall to the bottom of the Raisin Bran box: the smaller bits (stems and dust) fall through fine holes in the belt to return to the compost heap.

Finally, workers pack the leaves into large bales. The leaves are now ready to be sent on to another factory for their next adventure, where they'll transform from flaky tencha leaves into the fine emerald powder called matcha.

Watching the folks at Nishi Seicha make tea is both fascinating and mundane. The factory takes in raw tea and outputs it in a different but still undrinkable form: damp, unrefined tencha that requires cold storage to keep from rotting. If the factory were swept clean of tea leaves and you didn't work in the tea business, you'd have no idea what kind of factory it was: like every factory, it's a shed full of large, noisy machines and conveyor belts.

Except for the smell, that is. If the aroma outside the factory is enticing, inside it's intoxicating. The workers are long inured to it, but I kept taking conspicuous breaths. It smells like a cup of tea with a roasty mineral funk, so strong that it might caffeinate you right through your pores.

The Tasting Room

While the machines are humming and steaming and passing tea leaves among themselves, Takahashi or Hiroki Nishi or another factory worker will regularly taste the tea. A professional green tea tasting is like a coffee cupping and quite different from the way you'd enjoy a cup of the beverage in your easy chair.

Hiroki placed scoops of tea leaves into several cups and added boiling water. To measure the leaf quantity precisely, workers at the factory use a low-tech method: an old-fashioned balance scale with yen coins on one side and tea leaves on the other. One yen equals one gram.

Hiroki, Takahashi, and I used flat tea strainers to lift the leaves to our noses and sniff them. After letting the tencha infuse for a couple of minutes, we removed the leaves and sipped the tea.

Tea brewed this way, with unfinished leaves in boiling water, is not delicious; it's coarse and overextracted. The goal is to quickly identify dominant flavor notes and, especially, any flaws. Like high-quality sencha and other brewed green teas, this tencha had a balance of sweetness and astringency, that mouth-puckering sensation common to grape skins, persimmons, and strong tea. Unlike those teas, however, there were clear matcha notes: an additional level of sweetness, a pleasant, rounded bitterness, and a lip-smacking umami finish. To taste all of that, however, I had to fight down the part of my brain saying, "Ow! This is too hot, and it smells like someone let the kettle boil dry with tea leaves in it."

I asked Hiroki what happens if something is seriously wrong with the tea when he tastes it. Is there a big red "shut it down!" button, like in Ghostbusters?

"No, everything is controlled separately," he replied. Besides, they don't shut down production if the tea is defective. "We just have to sell it for a lower price." That's an uncommon scenario, but the factory does produce tea at various levels of quality and price for retailers to blend as they choose.

Like grains of sand at the beach, tea gets everywhere in a tea factory. My hands were speckled with tea for the rest of the day.

When I showered that night, the water ran green.

Where to Buy Matcha

For the most part, Nishi Seicha can't talk about who its customers are, but the company has a couple of public partnerships. Its sencha (tea leaves for brewing) are sold through Rishi Tea and its matcha is available via Aiya Matcha.

Here are a couple of other matcha purveyors I recommend:

Breakaway Matcha is imported by San Francisco food writer Eric Gower. He sells five varieties of matcha, including one organic. At $48 per 30-gram can and up, it's not cheap, but on a per-serving basis (that $48 can is about $1.60 per one-gram serving) it's comparable to drip coffee from a chain store, and a lot more satisfying.

O-cha sells high-quality matcha and other green tea, shipped directly from Japan at surprisingly affordable prices. Try the Uji Matcha Kiri no Mori ($13 for 30 grams) or the Organic Matcha Kaoru Supreme ($28).

Wherever you buy matcha, look for an intense green color, a pleasant aroma, and a balance of bitter and sweet. (Since matcha is sold in sealed cans, however, you won't see any of that unless you buy at a shop where matcha is served or sampled.) Avoid anything labeled "culinary matcha" or sold in a quantity larger than 30 grams, which indicates a lower grade.

When in Kirishima, you can taste and buy Nishi's teas at their shop, Kirin Shōten. For tips on brewing matcha yourself, read through our guide.

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