Tourism is key. Mariko Winery is designed for production and for show. In the main building, the tasting area and shop overlook the tank room and cellar on one side, vineyards on the other. Tours are available for visitors who want to dig deeper.  

But Katsuno thinks that tourism in the region needs to be strengthened. While a bus service connects the winery to a train station in the area, access remains a challenge. 

Across the river from the winery, the former post-town of Unnojuku, in Tomi, shows how travelers once passed through the valley. 

Established in the early 17th century, Unnojuku was a stop on the Hokkoku Kaido, one of a network of highways connecting Edo (now Tokyo) with the Sea of Japan. Travelers on the route included worshippers on their way to Zenkoji temple. 

Unnojuku’s attractive townhouses are now galleries, cafes, and restaurants serving Shinshu soba noodles, a Nagano specialty.

With Nagano one of the largest prefectures in Japan, travelers today can use shinkansen bullet trains to make much shorter time of this part of the valley. The journey between the cities of Nagano and Karuizawa takes around 30 minutes. There is a stop at Ueda, between the two popular destinations, but few people get off, according to Katsuno. “We need to work hard to make this area a destination in its own right,” he said.

Soy sauce maker Kikkoman Corp. established Manns Wine in the early 1960s, expanding into wine to complement the increasingly international flavor of Japan’s dining tables.  

The original focus at the Komoro Winery was on wine from Nagano’s ancient Ryugan grape -- also known as the Zenkoji grape after growing in the region around Nagano’s famous temple.

A 100-year-old Zenkoji vine, which inspired Manns Wine to pursue winemaking with Ryugan grapes, which it says were on the verge of extinction, now grows in the Japanese garden.

Although old by Chikumagawa Wine Valley standards, the half-century of winemaking at Komoro Winery is short. Teppei Nishihata, a winemaker at Komoro Winery, sees this as a positive. “This is just the beginning. There’s so much potential ahead,” he said.

Manns Wine explores this potential through its flagship Solaris series as it seeks to develop premium wines for the global stage. According to Komoro Winery, it has a rare asset in Nishihata, who is one of the few winemakers in Japan holding France’s national qualifications in both winemaking and wine-grape cultivation. 

Among 32 varieties of grapes cultivated at the winery, the focus is on Chardonnay and Sauvignon Blanc for white wines, Cabernet Sauvignon and Merlot for reds.

Nishihata, 45, says there is still much to learn about the land around Komoro. The differences in elevation within the city alone, he says, present opportunities for winemakers that have since come to the area to develop their own interpretations of Komoro wine or that of the valley. 

“Our winery alone does not make this a wine region. When we find a common thread among the wineries here, that's when we can define its character,” he said.

With around half of Nagano Prefecture's 90 wineries located in the Chikumagawa Wine Valley, winemakers realizing the region’s potential look set to have a significant impact on the identity of Nagano wine.