Mejiro Kōgaku Kōgyō K.K. (目白光学工業㈱) was a Japanese company, which produced the Honor S1 Leica copy from 1956. It seems that the project was initially developed by Daiichi Kōgaku on an original design by Kumagai Genji, then rescued from the failed Daiichi company by some individual (see Honor S1). That person was perhaps Yamashita Kamenosuke (山下亀之助), member of the Meguro company who wrote an article on the camera in an issue of Shashin Kōgyō.
The Mejiro company was specially created to manufacture the Honor S1. The camera was distributed by Zuihō Kōgaku Seiki from the start, and Mejiro, presented at the time as a "brother company", was perhaps founded with financial support from Zuihō. From autumn 1958, the documents mention Zuihō as the maker and distributor of the Honor, and all trace of Mejiro is lost, certainly because it was absorbed into Zuihō.
- Yamashita, pp.105–6 of Shashin Kōgyō August 1956. This magazine frequently contained articles written by top designers of their respective companies.
- Announce of the Honor in Asahi Camera July 1956, reproduced in Awano, p.7 of Camera Collectors' News no.37, mentioning Mejiro as a new company: 製造元は東京の目白光学という新しい会社で.
- Announce of the Honor in Asahi Camera July 1956, reproduced in Awano, p.7 of Camera Collectors' News no.37: 発売元の瑞宝光学精機[...]とは兄弟会社.