Japan's auto parts industry developed through keiretsu (affiliated supply chain) relationships with automakers, with Toyota Group companies such as Denso, Aisin, and Toyota Industries achieving global scale. Denso grew into the world's second-largest parts maker in thermal systems and powertrain controls, with revenue exceeding $40 billion. Aisin maintained a top global share in automatic transmissions but faces structural challenges from declining AT demand due to EVs. Outside the keiretsu, Bridgestone holds the world's No. 1 position in tires with over $30 billion in global revenue. The EV shift and CASE (Connected/Autonomous/Shared/Electric) transformation are simultaneously reducing engine-related parts demand while increasing the importance of software and electronic components—marking a turning point where traditional 'integral architecture' expertise alone is no longer sufficient.
Founded in 1936. Building on insulator technology, the company established the leading domestic market share in spark plugs and expanded into semiconductor package substrates. As a global manufacturer of automotive spark plugs, it has continued to grow alongside advances in engine technology.
Established in 1926. Originating from Sakichi Toyoda's automatic loom manufacturing, the company became the source of Toyota Motor. Diversifying into forklifts, car air-conditioning compressors, and textile machinery, it built a multi-business foundation as a core member of the Toyota Group.
Founded in 1949. Spun off from the electrical components division of Toyota Motor, the company established a leading domestic position in automotive electrical parts. Expanding into engine control, air conditioning, and safety systems, DENSO has become a global supplier driving the transformation of mobility society through ADAS and electrification technologies.
Founded in 1931. Originating as a division of Nippon Tabi, the company grew as a specialized tire manufacturer. Through the acquisition of Firestone in the U.S., Bridgestone rose to become one of the world's largest tire makers, overcoming quality issues to establish a global management structure.