Yamamoto Lock Machine (formerly Yamamoto Iron Works) Toilet

Yamamoto Rock Machine (Former Yamamoto Ironworks) Lavatory Block

Eighteen square meters. That is the entire footprint of the smallest building on Japan's national register at this site, a single story timber shed with an iron sheet roof standing parallel to the west side of Factory No. 1. It was built around 1939 as the lavatory for the men working in the shops, and it was registered as a cultural property alongside the factories in 2016.

Cultural property registers are not usually where one finds a works toilet. The reason this one is there has little to do with architecture and a great deal to do with what the building was equipped with.

The Agency for Cultural Affairs record notes two details. The glazing was doubled against the cold. And the block was plumbed for flush sanitation from the day it was built. Tojo sits in the Chugoku Mountains in the northeast of Hiroshima Prefecture, where winters are long, and a rural factory town in the late 1930s had no reason to expect either feature. The national record describes the building as assembling the advanced technology of its time and as evidence that the plant was built with hygiene in mind.

Why It Was Registered

The lavatory block became a Registered Tangible Cultural Property on 25 February 2016, No. 34-0160, in the 83rd round of registrations. Seven other buildings belonging to the company were registered on the same day, and an eighth, the former head office and main house on the town street, followed in December 2024.

Registration, established in 1996, is the lighter of Japan's two systems for protecting buildings. Where designation as an Important Cultural Property or National Treasure carries strict controls suited to older and rarer structures, registration works through notification rather than permission and is aimed at the modern building stock still in daily use. It is what makes it possible to place a factory lavatory on a national register at all. Under the older system the question would never have arisen.

What was registered here is not a single building so much as a way of running a company. Across the road from the shops stand the former dormitories: a family block, a block for single workers with a 59-meter corridor of ten-mat rooms, and a building holding a dining hall below and a recreation room above. Nearby is the youth school, whose upper floor held six classrooms for four years' worth of apprentice training, and where, according to Shobara City, that training continued into the late 1970s. The lavatory block belongs to the same account. A company that built schoolrooms and a recreation hall for its workers also gave them heated glazing and running water at the end of the shop.

What to Look For

The plan is straightforward and worth knowing before you see it. The western half holds the water closets. The eastern half holds the urinals and the washing trough, set out in a row. In a building of eighteen square meters, that division is the whole of the design.

The doubled glass is the detail to look for. Two layers of glazing in a small outbuilding in 1939 was an expense with no purpose beyond making the room bearable in a Tojo January, and it is the kind of decision that tells you more about an employer than a company history does.

Set against Factory No. 1 immediately to the east, 78 meters long and roofed with a raised central bay and a monitor above it, the little block reads almost as an afterthought. It was not one. The two were part of a single program of building that ran through the 1930s, and the smaller structure has survived at a period when works buildings of this kind were routinely demolished as plumbing was modernized.

Practical note: the site is a working factory on private land, closed to casual visitors. Volunteers involved in the preservation of the group have arranged occasional open days with the company, in some years coinciding with the Otoori festival in early November, when a modest admission has given access to the interiors, including this building. Nothing is scheduled annually, so ask the Shobara tourist association before making the journey. The exteriors of the factory group can be seen from the public road, though the lavatory block stands behind the main shops and is difficult to make out from outside.