Re: Eight-sole sandals

In old days, they were called "board backing sandals".
The backings were made of boards of Japanese cedar or something, and on top of the boards, usual sandals were attached. The split boards made walking easier, they said.
They were popular among workers of small factories. Black tabi socks and the sandals were styles specific to them. At spring factories around Kawasaki and Kamata, lathe operators in such sandals were seen frequently.
Besides, they were used in Tokyo Gas factories. Although no factories are present today as all the gas has become natural gas, coal was gasified by smoking in the past for city gas supply. The factories for the gasification were present in Omori, Toyosu, Negisi, etc. where workers on brick kilns wore the sandals too. Many canvas shoes were used in the factories, but rubber-soled shoes couldn't be used on kilns, and thus the board backing might be valuable.

From Mr. Awata (Male) born in 2nd year of Showa (1927)

Reading an article of The Yomiuri Shimbun dated May 30th, He provided the newspaper company with the information.