Founded in 1921, Koyo (Koyo Seiko) is a Japanese R&D-type manufacturer of comprehensive functional products, with 6557 employees. As one of Japan's four main bearing manufacturing groups, KOYO SEIKO owns world’s top production and control equipment, with eight main factories in Tokyo, Nara, Hikita, Toyohashi, Takamatsu, Tokushima and Kameyama in Japan, (all pass the ISO9001 certificate). Koyo Seiko has several overseas production facilities and research institutions across Europe, Asia, North and South America.

In 1st Jan. 2006, Koyo Seiko and Toyoda Machine Works Ltd have been merged. After combination, the new company name is Jtekt Corporation.