Sansho Shrine Hei-Haiden: A Masterwork of Shiwaku Carpentry on Honjima Island
On the peaceful shores of Honjima Island, the central island of the Shiwaku archipelago in the Seto Inland Sea, stands Sansho Shrine — a sacred site that embodies centuries of maritime heritage and architectural mastery. The shrine's Hei-Haiden (a combined offertory hall and worship hall) is a remarkable example of late Edo-period shrine architecture, registered as a national Tangible Cultural Property in October 2022. This building stands as one of the finest surviving works of the legendary Shiwaku carpenters, a group of master builders whose skills were forged in the shipyards of the Seto Inland Sea and refined in the construction of some of Japan's most celebrated temples and shrines.
What Is the Hei-Haiden?
The Hei-Haiden of Sansho Shrine serves a dual purpose within the shrine complex. The haiden (worship hall) is the space where visitors offer prayers and pay their respects, while the heiden (offertory hall) connects the worship hall to the main sanctuary (honden) at the rear. This integrated design creates a seamless passage from the public worship space to the sacred inner sanctum, reflecting a thoughtful architectural approach that honors both practical function and spiritual significance.
The building features a three-bay front façade and two-bay side elevation, constructed in the irimoya-zukuri (hip-and-gable) style with hon-kawara (formal tile) roofing. Its most striking feature is the layered arrangement of decorative gables on the front elevation: a chidori-hafu (plover gable) rises from the main roofline, while a karahafu (cusped gable) crowns the entrance canopy below, creating a dynamic, multi-tiered silhouette that conveys both elegance and grandeur.
Why Was It Designated a Cultural Property?
The Hei-Haiden was registered as a national Tangible Cultural Property on October 31, 2022, together with the adjacent Honden (main hall). The designation recognizes this building's exceptional value on several grounds.
First, the Hei-Haiden is considered a precious example of shrine architecture from the final period of Shiwaku carpenter activity. As the Shiwaku shipbuilding tradition declined in the late Edo period, many craftsmen transitioned to temple and shrine construction, channeling their extraordinary woodworking skills into sacred architecture. The Hei-Haiden represents the culmination of this tradition, displaying the full range of techniques that the Shiwaku carpenters had perfected over generations.
Second, the building's decorative carvings demonstrate remarkable technical accomplishment. The mizuhiki-kōryō (ornamental rainbow beams), kaerumata (frog-leg struts), tasuki (bracket carvings), and the sculptural elements of the entrance canopy all exhibit a high degree of artistry and craftsmanship. These carvings are not merely decorative but serve as a vivid record of the Shiwaku carpenters' sophisticated understanding of form, proportion, and natural imagery.
The Legacy of the Shiwaku Carpenters
To fully appreciate the Hei-Haiden, it is essential to understand the remarkable history of the Shiwaku carpenters. The Shiwaku Islands, situated at the heart of the Seto Inland Sea, were home to a powerful maritime community that served successive rulers from the Fujiwara regents to Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu. The islanders' exceptional shipbuilding skills — demonstrated most famously when 35 of the 50 crew members aboard the Kanrin Maru, the first Japanese ship to cross the Pacific Ocean in 1860, were from Shiwaku — formed the foundation of their later achievements in architecture.
As the shipping industry evolved in the mid-Edo period and large Osaka-based shipping companies gained dominance, many Shiwaku shipwrights reinvented themselves as shrine and temple builders. Their deep understanding of wood, joinery, and structural engineering translated seamlessly into architectural carpentry. The Shiwaku carpenters went on to construct some of the region's most important religious buildings, including the five-story pagoda of Zentsu-ji Temple in Kagawa and the five-story pagoda of Bitchū Kokubun-ji Temple in Okayama, as well as numerous shrines and private residences across the Sanyo and Shikoku regions.
The Sansho Shrine Hei-Haiden is recognized as one of the finest examples of Shiwaku carpentry from the group's later period, making it an invaluable record of this distinguished architectural tradition.
Highlights and Things to See
The most captivating aspect of the Hei-Haiden is its elaborately carved façade. The layered gable arrangement — the sweeping curve of the karahafu entrance canopy beneath the triangular chidori-hafu above — creates a visually striking composition that draws the eye upward. Each element is adorned with carvings that showcase the Shiwaku carpenters' mastery: flowing wave patterns on the rainbow beams, naturalistic floral and animal motifs on the frog-leg struts, and dynamic three-dimensional figures on the bracket carvings and kibana (decorative nose pieces) at the beam ends.
Take time to examine the transition from the Hei-Haiden to the Honden at the rear. The offertory section extends from the back of the worship hall to connect with the main sanctuary, which sits on a distinctive double-layered cut-stone platform with a kamebara (turtle-belly) base. The Honden itself, a one-bay nagare-zukuri (flowing) style structure built around 1830, features equally impressive carved panels, side screens, and railing details.
The shrine grounds offer a tranquil setting, shaded by mature trees and framed by views of the Seto Inland Sea. The quiet atmosphere of the Ikonohama settlement, far from the tourist crowds, allows visitors to contemplate these architectural treasures at their own pace.
Exploring Honjima Island
Sansho Shrine is located in the Ikonohama district on Honjima Island, and a visit pairs naturally with exploration of the island's many other cultural attractions. Honjima is the largest and most historically significant of the Shiwaku Islands, with a rich heritage stretching back centuries.
The Kasashima district, on the northern coast of the island, is designated as a national Important Preservation District for Groups of Traditional Buildings — the only such designation in Kagawa Prefecture. Here, narrow lanes wind between beautifully preserved merchant houses featuring latticed windows, white plaster walls, and namako-kabe (sea cucumber) walls, all built by Shiwaku carpenters in the late Edo through early Showa periods.
Other highlights include the Shiwaku Kinbanjo, an Important Cultural Property that served as the administrative headquarters for the Shiwaku Islands during the Edo period, where visitors can see vermillion seal documents granted by Nobunaga, Hideyoshi, and Ieyasu, as well as artifacts related to the Kanrin Maru voyage. The Chitose-za, a traditional kabuki theater built by Shiwaku carpenters in 1862, features an impressive revolving stage and is considered one of the thirty most important historic theater stages in Japan.
Rental bicycles are available at the port terminal and are the ideal way to explore the island, which has a circumference of approximately 16.4 kilometers. The Shin-Zaike coastline offers spectacular views of the Seto Ohashi Bridge spanning the sea toward Okayama.
Access and Practical Information
Honjima Island is served by Honjima Kisen ferries departing from Marugame Port. The ferry crossing takes approximately 35 minutes, with around six to eight departures daily. A faster passenger-only vessel completes the journey in about 20 minutes on select departures. Marugame Port is easily reached from JR Marugame Station on the JR Yosan Line, about a 10-minute walk north toward the waterfront.
From the Tomari Port terminal on Honjima, Sansho Shrine in the Ikonohama district can be reached by bicycle in approximately 15 minutes or on foot in about 30 to 40 minutes. The island has no convenience stores, so visitors are advised to bring food and drinks from the mainland. A limited number of dining options are available near the port area.
On the 20th of each month, Marugame City offers free ferry passage to the Shiwaku Islands, providing an excellent opportunity for budget-conscious travelers to visit.
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Q＆A
- What are the Shiwaku carpenters, and why are they important?
- The Shiwaku carpenters were a renowned group of master builders based on the Shiwaku Islands in the Seto Inland Sea. Originally skilled shipwrights who served Japan's most powerful leaders, they transitioned to temple and shrine construction in the late Edo period, building notable structures such as the five-story pagodas of Zentsu-ji and Bitchū Kokubun-ji temples. Their work is recognized for exceptional woodworking skill and elaborate decorative carvings.
- Can I enter the Hei-Haiden to see the carvings up close?
- As an active place of worship, the interior may not always be accessible. However, the most impressive carvings — including the karahafu entrance canopy, rainbow beams, and bracket sculptures — are visible from the exterior. The Shiwaku Daiku Kenshokai (Shiwaku Carpenters' Memorial Association) occasionally organizes special viewing events; checking their website before your visit is recommended.
- How do I get to Honjima Island from major cities?
- From Takamatsu, take the JR Yosan Line to Marugame Station (approximately 40 minutes), then walk about 10 minutes to Marugame Port and board the Honjima Kisen ferry (approximately 35 minutes). From Okayama, you can also access the island via ferry from Kojima Port. The island can be comfortably visited as a day trip from either city.
- What is the best season to visit Sansho Shrine and Honjima Island?
- Spring (March to May) and autumn (October to November) offer the most pleasant weather for exploring the island by bicycle. The mild Seto Inland Sea climate makes visits comfortable during much of the year, though summer can be quite hot and humid. Winter visits offer the advantage of fewer tourists and crisp, clear views of the Seto Ohashi Bridge.
- Is English signage available on the island?
- English signage is limited on Honjima Island. It is helpful to download offline maps and translation apps before your visit. The Kasashima Machinami Hozon Center (Townscape Preservation Center) offers some English materials, and the staff are welcoming to international visitors.
Basic Information
| Name | Sansho Shrine Hei-Haiden (三所神社幣拝殿) |
|---|---|
| Cultural Property Designation | Registered Tangible Cultural Property (Building), registered October 31, 2022 |
| Period of Construction | Late Edo period (estimated circa 1830–1868) |
| Architectural Style | Irimoya-zukuri (hip-and-gable roof), hon-kawara tile roofing, with chidori-hafu and karahafu gables |
| Dimensions | Three bays across the front, two bays on the sides |
| Location | 635 Urauchi, Ikonohama, Honjima-chō, Marugame City, Kagawa Prefecture |
| Owner | Sansho Shrine |
| Access | Honjima Kisen ferry from Marugame Port (approx. 35 min), then bicycle or walk to Ikonohama district |
| Admission | Free (exterior viewing); interior access may be limited |
References
- 三所神社本殿 — 文化遺産オンライン
- https://bunka.nii.ac.jp/heritages/detail/575722
- 地域から見る（丸亀市） — 文化遺産オンライン
- https://bunka.nii.ac.jp/heritages/region/37/37202
- 塩飽大工公式ホームページ（塩飽大工顕彰会）
- http://shiwaku.justhpbs.jp/
- 塩飽諸島：本島 — 丸亀市公式ホームページ
- https://www.city.marugame.lg.jp/page/1570.html
- 本島（香川県） — Wikipedia
- https://ja.wikipedia.org/wiki/%E6%9C%AC%E5%B3%B6_(%E9%A6%99%E5%B7%9D%E7%9C%8C)
- 時刻表・料金案内 — 本島汽船
- https://honjima-kisen.com/
- 笠島重要伝統的建造物保存地区 — GOOD LUCK TRIP
- https://www.gltjp.com/ja/directory/item/12135/
Last verified: 2026.03.26