A Historic Building Designated as a Nagano Prefectural Treasure
Honjin Iwanami Residence was designated a Nagano Prefectural Treasure in 2023. The surviving main building dates from around 1801, during the late Edo period, and is more than 220 years old.
The designation covers a total of nine buildings and structures, including the main residence, front gate, rear gate, side gate, document storehouse, charcoal storehouse, First and Second Storehouses, miso storehouse, and Kasuga Shrine.
Together, these buildings provide an exceptionally valuable picture of what an Edo-period honjin looked like. Unlike historic structures preserved only as isolated buildings, the complex retains multiple elements of the original estate and conveys the scale and character of a prestigious post-town residence.
A Historic Connection with Princess Kazunomiya and Emperor Meiji
One of the most fascinating chapters in the history of Honjin Iwanami Residence came in 1861, when Princess Kazunomiya, younger sister of Emperor Komei, stayed here while traveling to marry Tokugawa Iemochi, the 14th shogun of the Tokugawa government.
Her marriage procession was an enormous undertaking involving a vast retinue, and Shimosuwa-juku is said to have been exceptionally busy during her passage through the town.
Emperor Meiji also stopped at the residence as a resting place. Visitors today can see the upper guest room associated with Princess Kazunomiya and Emperor Meiji and imagine the atmosphere of the period while viewing furnishings and architectural details connected with the residence’s distinguished guests.
A Celebrated Japanese Garden
One of the greatest highlights of Honjin Iwanami Residence is its magnificent tsukiyama-style stone garden, which has been selected as one of Japan’s notable 100 gardens.
More than 600 specially selected stones from across Japan were gathered for the garden, which took approximately 10 years to complete. The arrangement creates the impression of a remote mountain landscape, with rocks suggesting deep valleys and rugged peaks.
The garden also makes skillful use of its natural surroundings. The forest of Suwa Taisha Shimosha Akimiya forms a borrowed landscape beyond the garden, while water for the garden’s waterfall is drawn from the Shochigawa River. Architecture, water, stones, plants, and the surrounding forest are brought together as a single landscape.
Beauty Through the Four Seasons
The garden’s vegetation has remained largely unchanged since the Edo period, allowing visitors to enjoy a different expression in every season.
Azaleas bloom in spring, irises add color in early summer, autumn brings brilliant foliage, and snow transforms the garden into a quiet winter landscape. Rainy weather can be especially atmospheric, as the wet stones take on a deep, reflective beauty.
Looking out over the garden from the upper guest room is particularly memorable. The carefully arranged landscape resembles a traditional Japanese folding-screen painting, with the garden and distant scenery appearing to merge into a single composition.
Refined Kyoto-Style Sukiya Architecture
The architecture of Honjin Iwanami Residence is highly regarded for its sophisticated Kyoto-style sukiya-zukuri design. The Nakasendo was the major route connecting Kyoto and Edo, and many members of the imperial court and powerful feudal families traveled along it. As a result, the cultural influence of Kyoto can be seen in the refined design of prestigious residences such as this one.
One particularly striking feature is the bold structural design in which the eaves are supported by a single corner support post. The carefully calculated proportions of the individual rooms also demonstrate an exceptional sense of balance and elegance.
The refined composition is sometimes said to evoke the aesthetic of Katsura Imperial Villa in Kyoto, reflecting the high level of craftsmanship and design that was expected of an important honjin.
The Iwanami Family and the History of the Honjin
The history of the Iwanami family is said to reach back to the Kamakura period. The family was descended from the distinguished Ogasawara clan of Shinshu and served as the honjin and toiya of Shimosuwa from 1688 until the Meiji Restoration.
For generations, the family carried the considerable responsibility of managing one of the most important post towns on the Nakasendo while continuing to protect the residence and its surrounding property.
Today, the 28th head of the Iwanami family still lives at the residence and personally helps maintain the historic property. The fact that the building continues to function as a home while also being preserved as an important cultural heritage site gives the residence a special sense of continuity.
Shimosuwa-juku: A Historic Post Town and Hot Spring Destination
Honjin Iwanami Residence can be best understood by exploring the wider history of Shimosuwa-juku. It was the 29th post station from Edo on the Nakasendo and also marked the terminus of the Koshu Kaido.
During the Edo period, the post town had one honjin, one waki-honjin, and approximately 40 inns, welcoming travelers, merchants, officials, and feudal processions.
Shimosuwa was also unique as the only Nakasendo post town with naturally occurring hot springs. Travelers had been using the local hot springs since ancient times, and bathing became an important part of the town’s appeal.
Today, visitors can still experience this history through the traditional streets, public bathhouses, old buildings, and historic sites scattered throughout the town.
Explore the Historic Sites Around Shimosuwa
After visiting Honjin Iwanami Residence, travelers can continue exploring the area’s many cultural attractions. Suwa Taisha Shimosha Akimiya and Harumiya are both within the historic town, while the unusual Manji Stone Buddha provides another fascinating glimpse into local religious traditions.
The nearby Kaizuka, as well as the old Nakasendo and Koshu Kaido routes, offer further opportunities to explore the landscape and history that shaped Shimosuwa.
Standing where the two historic highways meet, visitors can look across the same landscape that generations of travelers once encountered on their journeys between Edo, Kyoto, and the provinces of central Japan.
A Journey into the Heart of Edo-Period Japan
Honjin Iwanami Residence offers a rare opportunity to experience the world of Japan’s historic post towns through an exceptionally well-preserved architectural complex and garden.
The buildings designated as Nagano Prefectural Treasures, the elegant stone garden, the connections with Princess Kazunomiya and Emperor Meiji, and the continuing involvement of the Iwanami family all give this residence a remarkable sense of historical continuity.
For travelers interested in Japanese history, architecture, gardens, and traditional culture, a visit here provides more than a glimpse into the past. From the same rooms and garden that once welcomed distinguished travelers, it is possible to imagine the journeys, ceremonies, and daily life of the Edo period.
Access
Honjin Iwanami Residence is approximately 10 to 15 minutes on foot from Shimosuwa Station on the JR Chuo Main Line. By car, it is approximately 20 minutes from the Suwa Interchange and about 15 minutes from the Okaya Interchange on the Chuo Expressway.
A visit to Honjin Iwanami Residence is an ideal way to experience the history, elegance, and enduring atmosphere of Shimosuwa-juku. Take time to admire the architecture and garden, then continue on foot through the historic post town and its sacred sites for a deeper appreciation of this remarkable corner of Nagano.