Kao Corp., the largest maker of bath and shower products in Japan, is seeking to at least double the size of its Vietnamese business to ramp up overseas growth amid a shrinking population at home.

"I want to double and triple the business in Vietnam," President Michitaka Sawada said in an interview. The company may build a new factory in Southeast Asia to strengthen the Vietnamese operations, he said, without specifying a time frame or investment amount.

Kao, the owner of Molton Brown cosmetics, is boosting its Vietnamese business as it plans to get much as 50 percent of its sales from overseas by 2020, compared with the current 27 percent.