New Project W BARREL: Pukupuku Brewing × Whiskey & Co.

An announcement about our new project and the launch of its first product.

About the New Project “W BARREL”

Whiskey & Co. was founded in June 2023 in Mishima City, Shizuoka Prefecture, as a distillery dedicated to establishing a new style: “Japanese Bourbon Whiskey Style”—a rare focus in Japanese whisky. True to the definition of bourbon, we use corn, rye, and malted barley, and mature our spirit in new American white oak barrels.

Last June we released “Little K,” a whiskey brand matured for under two years, which has sold out twice, and we recently released its third batch, Little K 2026. The Little K series has also won the Master Medal—the top award—at The World Whisky Masters 2025 in London, and the top gold award at the Tokyo Whisky & Spirits Competition 2026, one of Asia's largest spirits competitions.

Our newly launched project, “W BARREL,” focuses on finding new uses for the barrels that once held our bourbon-style whiskey. Just as with Little K, we lend out these barrels to businesses across every industry, crossing genre boundaries to create entirely new products together.

As the memorable first release under W BARREL, we're launching a collaboration product with Fukushima-based “Pukupuku Brewing,” who are pushing the boundaries of sake-making, on June 27, 2026!

W BARREL: Pukupuku Brewing × Whiskey & Co.

Woody, sweet aromas resonate with the rich flavor of rice. A naturally fermented all-koji sake, fermented and matured in bourbon-style whiskey barrels, with rich umami and a beguiling acidity. This is a challenge to not only mature but also primary-ferment the mash inside the barrels that once held Whiskey & Co.'s bourbon-style whiskey “Little K.”

The mash inside the barrel is a “wild yeast and lactic-acid, natural-fermentation, all-koji sake”—in other words, an all-koji sake fermented at room temperature by wild yeast and lactic acid bacteria. The result is a one-of-a-kind bottle where the rich vanilla-like barrel aroma from the bourbon barrel intertwines intricately with the powerful umami and acidity of the room-temperature-fermented all-koji sake.

Barrels with a strong “bourbon style” character—carrying the pronounced nuance of new oak—bring powerful notes of raw whiskey spirit, toasted oak, vanilla, and caramel. Pairing this with an ordinary sake would let the barrel's strength overwhelm the balance. So the question became: how do we make the barrel's power resonate with the delicacy of a rice-based sake? The answer we chose was “zenkoji-jikomi”—an all-koji brewing method that uses only rice koji, with no additional steaming rice.

While ordinary sake uses koji rice for only about 20% of its total rice, this brew uses 100% koji rice, pushes the water ratio to its limit, and ferments at room temperature—drawing out the rich umami of the rice koji to its fullest. White koji is used alongside wild yeast and lactic acid bacteria fermenting at room temperature, bringing out a powerful yet beguiling acidity. The alcohol is finished at a relatively high 10% for Pukupuku Brewing, and that acidity balances lightness with depth. It's precisely because this all-koji sake has such rich umami and punchy acidity that it can fully receive the barrel aroma of “Little K,” creating a truly unique harmony.

The rice used is organically and naturally grown rice from the Hamadori region, milled to a low 90% seimaibuai and used without waste. The white koji uses organically grown “Aikoku” rice from Nemoto Organic Farm in Minamisoma City, and the yellow koji uses naturally grown “Kamenoo” rice from Kohei Iseki in Okuma Town.

On the palate, a vivid acidity leads a rich, full-bodied flavor, followed by a gentle spread of sweet vanilla and woody notes from the whiskey barrel. We recommend warming it to the mid-teens (Celsius) and enjoying it in a wine glass or another vessel that captures the aroma well. It also makes a wonderful pairing with food—try it with richly spiced simmered pork, smoked nuts, cheese, or dried fruit!

A flavor born where the ancient technique of “zenkoji-jikomi” meets and blends with the different culture of the “bourbon barrel.” A truly once-in-a-lifetime taste. Please enjoy this special moment while it lasts.

P.S. We let the angels take a bit too much of their share, so quantities are quite limited. :(

Product Details

Category: Other brewed sake
Ingredients: Rice koji (produced in Fukushima Prefecture)
Rice: Organically grown “Aikoku” from Odaka Ward, Minamisoma City, Fukushima (Nemoto Organic Farm); naturally grown “Kamenoo” from Okuma Town, Fukushima (Kohei Iseki)
Rice polishing ratio: 90%
Method: No added yeast or lactic acid bacteria, kimoto (native yeast)
Alcohol: 10%
Volume: 280ml
Planned release date: Saturday, June 27, 2026
Brewery: Pukupuku Brewing Co., Ltd.
Other: Requires refrigeration (below 5℃)

Where to Buy

Available in limited quantities (up to 5 bottles) at Bar Water Gate, adjoining Distillery Water Dragon. It's also distributed to select retailers by Pukupuku Brewing—see Pukupuku Brewing's note page for details.

Pukupuku Brewing's SNS

X: https://x.com/pukupukubrewing
Instagram: https://www.instagram.com/pukupukubrewing