Yoshiko Abe is about to turn 89, but that hasn't stopped her from going to the gym every day and trying the free-of-charge makeup course at her housing complex.

"It was really helpful," she said, all smiles and glowing after putting on foundation and pink lipstick, something she hadn't done in years.

Japan has the largest percentage of older citizens than any other country in the world. More than a quarter of Japan's population is 65 and older, at 36 million people. In about a decade, the ratio will be one in three.

No wonder the young-at-heart, like Abe, is a growing target for Japan Inc.

The market for older people is estimated to grow to more than 100 trillion yen ($650 billion) in size this year, according to a study by Mizuho Bank. And that business isn't just about remedies for sicknesses and old folks' homes but taps into solid consumerism.

The growth of artificial intelligence and robotics also offers promise for such services and gadgetry. Akira Shimizu, professor of business at Keio University, calls them "cool grandpas and cute grannies" who remain sensitive to trends, including the latest luxury and health products.

"They think about the clothing and makeup that express their style," he said.

From luxury cruises and "oldies" rock concerts, companies are leveraging the fact that older people these days remain active, go out with friends and on dates, so they want to dress up and look good, said Shimizu.

Maintaining one's looks is good physical exercise because it takes hand agility to open cosmetics tubes and draw eyebrows nicely, and massaging the face gets one's saliva glands going, according to Miwa Hiraku, the makeover class instructor from the Japanese cosmetics company Shiseido.

Shiseido Co., which started out as a pharmacy in 1872, said that makeup is not just good for your physical well-being but also your soul.

The company has been holding free makeup courses for older people across the country.

"Putting on makeup works as a switch to turn on your energy at the start of your day," said Hiraku, who vows to wear makeup even at 100. "It's not just about looking beautiful. It's about living a long healthy life."

Yoshihiko Hotta, 85, the only man in the class of about 30 people, didn't try the rouge but happily put on the hand cream and went along with all the exercise routines. While acknowledging he felt some effects of aging like sore legs, he declared with conviction: "I don't think age is relevant."