The Kerio is a Japanese leaf shutter, giving T, B, 25–150 speeds. It is listed as made by Miyoshi in the "Kokusan shashinki no genjōchōsa" ("Inquiry into Japanese cameras") compiled in April 1943. It is not known if it was an original Miyoshi product or if it was made by Proud before this company was absorbed by Miyoshi.
This list is perhaps incomplete. The fact that a camera appears in this list does not mean that all the variants were equipped.
- "Kokusan shashinki no genjōchōsa" ("Inquiry into Japanese cameras"), shutter item 18-V-2.
- Asahi Camera (アサヒカメラ) editorial staff. Shōwa 10–40nen kōkoku ni miru kokusan kamera no rekishi (昭和10–40年広告にみる国産カメラの歴史, Japanese camera history as seen in advertisements, 1935–1965). Tokyo: Asahi Shinbunsha, 1994. ISBN 4-02-330312-7.
- "Kokusan shashinki no genjōchōsa" (国産写真機ノ現状調査, Inquiry into Japanese cameras), listing Japanese camera production as of April 1943. Reproduced in Supuringu kamera de ikou: Zen 69 kishu no shōkai to tsukaikata (スプリングカメラでいこう: 全69機種の紹介と使い方, Let's try spring cameras: Presentation and use of 69 machines). Tokyo: Shashinkogyo Syuppan-sha, 2004. ISBN 4-87956-072-3. Pp.180–7. Shutter item 18-V-2.