All of the previous reviewers visited only one of the four locations that make up this WHS, the main site: the Tomioka Silk Mill. And to tell it right away: I did it the same way.
It doesn’t seem to be very difficult to visit at least one of the other locations, the distances from Tomioka are between 25 and 45 kilometres. However, this website estimates travel times from the silk mill by public transport between 75 and 100 minutes, including taxi rides and/or walking. So quite a lot of effort to see very little: a few empty shelves where the silkworm cocoons were raised (Takayama-sha Sericulture School), a farmhouse from the outside (Tajima Yahei Sericulture Farm), and a few foundation walls (Arafune Cold Storage). Thus, I decided to skip the other locations in favour of some non-WHS stuff in Tokyo.

But now to the main thing:
The Tomioka Silk Mill was built in the early years of the Meiji restoration and represents a milestone in the transformation of Japan into an industrialized nation. In this regard, it is closely related to the "Sites of Japan's Meiji Industrial Revolution" which were inscribed in the WH list only one year after Tomioka. Apart from the obvious differences to coal mining and steel production, Tomioka deserves its own inscription because it illustrates the fusion of Japanese tradition and modern European technology. Through this modernisation the mass production of silk was established and Japan became the leading export nation for raw silk.

The first thing you see when you enter the grounds is the façade of the east cocoon warehouse. It is a timber-frame brick construction with glass windows. Three of these long buildings are the core of the silk mill in the shape of a large U. The western style cannot be denied, but local materials and techniques have been used. As the name suggests, the warehouse was used to store the silk cocoons, the photo shows the second floor. A film is shown on the ground floor and an exhibition explains the silk production and the history of the mill, both in Japanese only (translations into English are available at the ticket counter, the audioguide does not include the exhibition).
The west cocoon warehouse is currently not accessible. The two warehouses are connected by the silk reeling plant: two long rows of reeling machines. Here the silk threads were automatically reeled off from the cocoons. However, the machines are wrapped in plastic foil, there is only a video that shows how the procedure works. I remember, that at comparable sites in the UK, such as Masson Mill (Derwent Valley) or Saltaire, the machines are operational and the functionality was demonstrated live. This should also be possible in Tomioka, the facilities are much newer, they were used until the late 1980s when the factory was closed.
Only the east warehouse and the silk-reeling mill are open to visitors, the other buildings can only be viewed from the outside or are not accessible at all. In September 2019, the visiting area was limited to less than half of the complex. However, construction work was carried out in the west warehouse and the silk drying facility, probably they will be open in the near future. It would also be nice to see the interior of the dormitories for the female workers or the colonial-style director's house. All of these buildings appear to be well preserved.

The Tomioka Silk Mill is an interesting site and represents an important period in Japan's history. But there is much room for improvement in the way the site is presented to visitors. At present, the site appears unfinished. However, the ongoing restoration work indicates that progress can be expected. Future reviewers may be able to report improvements.