Koken Ltd., together with its subsidiaries, produces and sells occupational personal protective and environmental quality improvement equipment in Japan. It operates through Mask-Related Business, Environmental-Related Businesses, and Other Business segments. The company offers clean air solutions, including KOACH, a clean zone creator; and KOKENLAMINAR, a push-pull ventilation system. It also provides surgical masks. In addition, the company offers respirators, including particulate respirators, chemical cartridge respirators, and gas masks for industrial use; and respirators for general consumers; and protective clothes, earplugs, and face shields. The company was founded in 1943 and is headquartered in Tokyo, Japan.