The Sluice That Never Stopped Working
Iguchi Yonban-hama Kita Maruhi (井口四番浜北丸樋) is a late Edo-period granite sluice structure on the shore at Iguchi, Kamiura-cho, Imabari City, Ehime Prefecture, entered on the national register as a Registered Tangible Cultural Property on 31 January 2003. The Agency for Cultural Affairs dates it to the closing decades of the Edo period, between roughly 1830 and 1867, and records it as a single structure of stone, 7.8 meters long.
It occupies the northern edge of what was once the fourth salt field at Iguchi, on the eastern coast of Omishima. Salt fields here were counted in numbered plots called hama; a hi is the sluice cut through an embankment to move water, and maru refers to the curved stone wall built around the outlet. Three such structures survive along this shore. Iguchi Yonban-hama Kita Maruhi is the smallest of them, and the only one the national record still describes as doing its job.
Built Where the Embankment Turns
The other two sluices on this coast sit on the eastern side of the field, facing open water along a straight run of sea wall. Iguchi Yonban-hama Kita Maruhi does not. It was placed on the northern side, on the stretch where the embankment leaves the shoreline and bends back toward the land.
That corner is a different hydraulic problem. Water arriving obliquely piles against the inside of the angle, and the drainage of the field's northern margin gathers there rather than spreading along a face. The response was a wall of granite curving outward in a semicircle, 7.8 meters around the outlet, holding the opening clear while presenting a rounded surface to whatever the weather brings in.
The masonry is simpler than its neighbour's. The face rises almost vertically and is laid throughout in tanizumi, a system in which the stones are set on the diagonal so the joints form a lattice of diamonds. Iguchi Yonban-hama Minami Maruhi, about 100 meters to the southeast, switches partway up from battered diagonal work to level coursing; here there is no such change. At 7.8 meters against 8.5 and 12 for the other two, this was the least demanding of the three sites, and the stonework says so.
Altered, and Still in Use
The Agency for Cultural Affairs record contains a sentence that sets Iguchi Yonban-hama Kita Maruhi apart from most registered structures. It notes that the sluice itself has been rebuilt, and that the structure nevertheless continues to perform its drainage function today.
Both halves of that statement matter. The salt fields are gone, filled and turned over to other uses during the twentieth century, and with them went the reason the outlet was cut. What remains is a working drain: rainwater and runoff from the land behind the embankment still leave through this opening, as they have since the closing years of the Edo period. The granite wall around it is original. The channel running through has been renewed at some later date, which the record states plainly rather than glossing over.
Registration accommodates exactly this. The Registered Tangible Cultural Property framework covers buildings and structures that are still in service and that have been altered in the course of staying useful, which is why a modified but functioning sluice can appear on the national register alongside untouched monuments. The criterion applied here, on 31 January 2003, was that the structure cannot easily be reproduced. Its registration number is 38-0030, in the thirty-fifth round, with public notice on 26 February of that year. Imabari City owns it.
Visiting Iguchi Yonban-hama Kita Maruhi
The site is outdoors on the shore, with no gate, no admission charge, no set hours, and no restriction on photography. There is no visitor centre, no interpretive panel, and no dedicated parking. Adjoining land is partly private, and the stonework is a registered structure rather than somewhere to climb, so view it from the public road and the shoreline alongside.
Tide decides how much is visible. Around low water the curve of the wall and its footing stand clear; at high water the lower courses go under. Because this sluice still drains, watching it on an outgoing tide or after rain shows something the other two cannot: water actually moving through. A tide table for the Imabari area is worth consulting before you set out.
Iguchi lies on the eastern coast of Omishima, roughly two kilometers north of the Omishima interchange on the Shimanami Kaido expressway and about 1.6 kilometers northwest of the Tatara Shimanami Park roadside station. The Iguchi-ko bus stop, served by express buses running from in front of Imabari Station toward Omishima, is only a short walk away, though services differ in which stops they call at and the timetable is worth checking first. Cyclists on the Shimanami Kaido pass close by. Iguchi Yonban-hama Minami Maruhi stands about 100 meters to the southeast and the Former Iguchi Sanban-hama Maruhi beyond it, so all three can be seen in a single short walk.
- 📍 Plan Your Visit to Ehime
- Find tours, activities & transport passes near Iguchi Yonban-hama Kita Maruhi
- [ Dogo Onsen & Matsuyama Castle Relaxation Tour ]
Q&A
- What is Iguchi Yonban-hama Kita Maruhi, and when was it built?
- It is a stone sluice structure on the east coast of Omishima in Ehime Prefecture, built to drain surplus water from a salt field. The Agency for Cultural Affairs dates it to the late Edo period, roughly 1830 to 1867, and records it as a single structure of stone, 7.8 meters long.
- Is Iguchi Yonban-hama Kita Maruhi still functioning?
- Yes. The national record notes that the sluice channel itself has been rebuilt at some point, but that the structure still carries out its drainage role. The salt field it once served is gone, while runoff from the land behind the embankment continues to leave through the opening.
- How does Iguchi Yonban-hama Kita Maruhi differ from the other sluices at Iguchi?
- It sits on the northern side of the field, where the embankment turns inland, rather than on the straight eastern sea wall. At 7.8 meters it is the smallest of the three, against 8.5 meters for the Former Iguchi Sanban-hama Maruhi and 12 meters for Iguchi Yonban-hama Minami Maruhi, and its face is laid throughout in diagonal tanizumi masonry with no change of system partway up.
- Can I visit Iguchi Yonban-hama Kita Maruhi, and is there an admission fee?
- Yes, and there is no charge. It stands outdoors on the shore with no gate and no set hours, and photography is unrestricted. There is no visitor facility or dedicated parking, and neighbouring land is partly private, so view it from the adjacent public road and shoreline.
- How do I get to Iguchi Yonban-hama Kita Maruhi?
- By car it lies about two kilometers north of the Omishima interchange on the Shimanami Kaido, and roughly 1.6 kilometers northwest of the Tatara Shimanami Park roadside station. By bus, take an express service for Omishima from Imabari Station and alight at Iguchi-ko, a short walk from the shore. Check the timetable in advance, as not every service calls there.
Basic Information
| Name | Iguchi Yonban-hama Kita Maruhi (井口四番浜北丸樋) |
|---|---|
| Location | Coast of Iguchi, Kamiura-cho, Imabari City, Ehime Prefecture (Omishima) |
| Designation | Registered Tangible Cultural Property (structure), registration number 38-0030 |
| Year Designated | Registered 31 January 2003, public notice 26 February 2003 (35th round of registrations) |
| Quantity | 1 structure |
| Dimensions | Stone construction, 7.8 meters long |
| Owner | Imabari City |
| Public Access | Outdoors on the shore. Viewable at any time, no admission fee, no visitor facilities or dedicated parking |
References
- Agency for Cultural Affairs, National Cultural Properties Database: Iguchi Yonban-hama Kita Maruhi
- https://kunishitei.bunka.go.jp/heritage/detail/101/00003153
- Cultural Heritage Online: Iguchi Yonban-hama Kita Maruhi
- https://online.bunka.go.jp/heritages/detail/183063
- Agency for Cultural Affairs, National Cultural Properties Database: Iguchi Yonban-hama Minami Maruhi
- https://kunishitei.bunka.go.jp/heritage/detail/101/00003152
- Imabari City Division of Cultural Promotion: Cultural Properties of the Kamiura District
- https://www.city.imabari.ehime.jp/bunka/bunkazai/bunkazai/kamiura.html
Last verified: 2026.09.03