Ako Shōkai was a Japanese company that sold a 4.5×6 folder in 1941–2 under the names Semi Ace, Semi Ako and Semi Metax. In the advertisements, Ako Shōkai was written AKO商會 in old writing, with uppercase letters. Its address at the time was Tōkyō, Kanda, Iwamoto-chō 18 (東京・神田・岩本町十八).
- Advertisements dated December 1941 and March 1942 reproduced in Kokusan kamera no rekishi, pp. 58, 60 and 99.
- 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. Items 3, 28 and 284.