Otowa Kōki Seisakusho (音羽光機製作所) is a Japanese company that made cameras called "Middl" (NB not "Middle") around 1952–3. Its logo is the scheme of a concave lens element, with the letters OKS inside (surely for Otowa Kōki Seisakusho).
Cameras:
- Middl 120-A (4.5×6 folder)
- Middl 120-Z (6×6 folder)
- Middl Flex (6×6 TLR)