Auto parts supplier DENSO Corp. said it could increase its stake in powertrain manufacturer Aisan Industry Co. Ltd. or transfer parts of its powertrain business to Aisan in a bid to strengthen cooperation as the industry faces a "once-in-a-century paradigm shift."

The Japanese companies on May 20 began reviewing their options to improve their powertrain businesses, including an option of Denso acquiring all Aisan shares owned by Toyota Motor Corp.

Toyota Motor owns a 28.75% stake in Aisan, while Denso owns an 8.73% stake and Toyota Industries owns a 7.57% stake in the company.

In April, Toyota and Denso agreed to merge the core electronic component operations of the two companies within the parts maker to "survive in this era of profound transformation."