Sengu

As the main hall of Izumo Taisha is a national treasure, all repair work involved in the sengu has been conducted under the guidance of the Agency for Cultural Affairs. All wood used must be from the same kinds of trees, and the tools used must also be traditional. This is done in order to preserve the techniques that have been used throughout history in the construction of Izumo Taisha. A sengu is an expensive endeavor; while the government subsidizes half of the total cost of 8 billion yen, the rest is covered by donations from around the country. It is also a very time-consuming process, taking at least five years from start to finish.

The latest sengu began on April 20, 2008, with a special ceremony to transfer the deity from the main hall to a temporary location known as the okariden for the duration of the sengu. Then, several opportunities were made available for visitors to the shrine to see the main hall’s ceiling, on which a brilliantly colored painting of clouds known as the Yakumo-no-zu is painted. Although the painting is as old as the shrine building, the brilliance of the colors gave no hint to viewers that it was almost 270 years old. The grounds of Izumo Taisha were packed with visitors who came for the chance to see something that is only made viewable to the public when a sengu occurs.

When these viewings were finished, the real work began. First, at the end of 2008, construction began on a temporary covering that would protect the main hall while construction was underway. Following its completion in late June of 2009, a second viewing of the main hall was held, making it possible for people to see the thickness and design of the building, including the roof, up close. After that viewing period, the ornamentation on the roof was removed and inspected, after which repair work went into full swing. While removing the bark from the roof, the way it had been placed was carefully inspected so that it could be replicated. Any other damaged material in the roof’s foundation was noted and marked for replacement, as were any other parts of the shrine that were in poor condition. So what happened to the bark once it had been removed? In the past, it would often be returned to nature, but according to current legal restrictions, that would be considered illegal dumping. Also, it couldn’t be burned, because it was once used as part of the shrine and had a special significance. So, some of the removed bark was used to make charcoal, which was then donated to different facilities in the prefecture. The remaining bark was separated into small parts and given to people who attended following viewings of the shrine.

When the roofing was completely removed, another series of viewings were held to allow people to see how the structure of the roof’s foundation was constructed. Repairs and replacements continued, and once the foundation had passed inspection, the reroofing began. The 640,000 strips of Japanese cypress bark needed to reroof the main hall had to be procured from trees throughout the country. However, this was not as easy as you may think. To get bark that can be used for roofing, naturally growing hinoki trees must be found and stripped of their bark, as this bark is too rough to be usable in roofing shrines. Once that bark is removed, it takes seven years for new bark to regrow. That bark, which is smoother and better suited to the roofing process, is then stripped off. Naturally, this process takes a considerable amount of time, and with the large amount of bark and unique lengths necessary for the roof, preparations were in motion long before the actual sengu began.

Using different lengths of bark, the roof gradually began to take shape. Special viewings were held again while the roof was being assembled, and later again when it had been completed. All of the copper plating that was used for ornamentation was cleaned and reused when possible, and replaced when not. During the examination of these plates, it was discovered that a special coating called channuri had been used to coat these copper plates during the sengu that was completed in 1881. New copper is somewhat weak when exposed to the elements, and channuri protects and strengthens it as it ages until the coating naturally falls off, revealing the now stronger copper plates below. It is made from a mixture of pine resin, lead, lime, and perilla oil with different natural coloring agents added. Due to the discovery of its prior usage, for the first time in 130 years channuri has once again been used on the copper plates on the main hall.

Currently, all of the necessary work has been completed on the main hall, and the covering has been removed. The final preparations are now in place, and the main work of this latest sengu will be completed with the return of the deity to the main hall in a ceremony on May 10, 2013. There are still other repairs that are scheduled, including reroofing all of the other shrine buildings on the grounds and some shrines that are in the surrounding area. This year will be a wonderful opportunity to come and see Izumo Taisha in its revitalized state.