Every morning, before her children go to school, and every evening, after putting them to bed, Mutsuko Tsuyuki turns on her son's Nintendo hand-held game console.
But while her six-year-old son uses the device to race computer-generated cars and battle demons, Tsuyuki is following her daily exercise regime.
"It has become a habit and I really think that I'm beginning to see the benefits of about 15 minutes of these brain exercises a couple of times a day," said the 37-year-old Yokohama housewife.
"My parents told me about it and my mother, in particular, really feels that it's doing her good as well."
Tsuyuki - and millions of Japanese like her - have caught on to the latest in a wave of gadgets and lifestyle choices that are being embraced as a way of warding off, or at least delaying, the onset of old age.
The software challenges people to complete simple arithmetic, draw Japanese characters on the touch screen and complete memory puzzles.
After completing the tests, the programme deduces their mental age based on the speed of their responses. With practice, a player's brain age gets younger as scores get better.
"We do not really look at it as a game but are marketing it as educational software"
Two versions of the game Brain Age have sold more than four million copies since the Kyoto-based Nintendo company first released the game in May last year.
Clever marketing has made it a hit with older people who have previously not played computer games but believe an active mind will help them stay mentally alert.
Nintendo is so impressed with domestic sales of the software that it released a US version on April 27 and European versions in English, Spanish, French, German, Italian and Danish, are due to go on sale in May.
"We do not really look at it as a game but are marketing it as educational software," Yuka Tanegashima, a spokeswoman for Nintendo, told Aljazeera.net, adding that it had sold well among older age groups.
The version that will be sold overseas will have a number of alternative problems to solve, including the sudoku numbers puzzle, Nintendo said.
"We are not sure how well it will do in the new markets, because we are not sure whether people there feel the same way as Japanese people do about taking care of both their physical and mental health," Tanegashima said.
"But we hope it proves equally popular."
'Train your brain'
Satoru Iwata, president of Nintento, has said he hopes the company sells two million copies overseas - and that the "train your brain" slogan appeals to older people.
The game was devised by Ryuta Kawashima, one of Japan's leading experts on brain imaging technology. Kawashima has also written two books on brain training.
Nintendo says exercising the
brain improves memory
In his research on the functions of the brain, Kawashima has determined that mental stimulation increases the flow of blood through the central areas of the brain, the crucial area for memory and thought processes.
By "exercising" the mind on a regular basis, one can invigorate the brain and improve memory.
Grey cell gymnastics?
Others, however, believe it is far too early to tell whether mental gymnastics are genuinely able to keep mental deterioration at bay.
"At the moment, we just don't have enough scientific evidence of effective ways to prevent dementia, or whether it is possible through a game such as this," said Takao Suzuki, vice director of the Tokyo Metropolitan Institute of Gerontology.
"But there are some researchers who believe that stimulation of the mind by various methods, including carrying out simple calculations, writing Japanese kanji characters and other methods of amusement may prevent or reduce dementia.
"That is one scientific point of view, but another point of view is that we should try everything and anything that might prevent an old person from suffering dementia, so this certainly can't hurt."
It is the very same belief - "it can't hurt" - that is driving the anti-ageing boom in this country.
Cosmetics giant Shiseido launched a face cream this year which contains microscopic capsules of a vitamin it claims help the skin to be "reborn".
Shiseido says the product has proved particularly popular with women in their 40s and 50s and sales are 20% higher than anticipated.
"Japanese society is in a difficult situation at the moment because we are about to experience a wave of baby-boomers suddenly retiring over the next two or three years"
Chairman of the Japan Senior Citizens Welfare Organisation
Elsewhere, restaurants that emphasise their use of natural or organic products are doing a roaring trade.
More people than ever before are signing up at fitness centres and beauty clinics, while cosmetic surgery is also on the increase. And it is not just for women, the traditional consumers in this sector. Men are also embarking on the search for eternal youth.
"Japanese society is in a difficult situation at the moment because we are about to experience a wave of baby-boomers suddenly retiring over the next two or three years," said Masami Ihara, chairman of the Japan Senior Citizens Welfare Organisation.
"Our population is ageing very fast - 40 million of the 120 million Japanese are 65-years-old or over - and we have many problems with the national pension and medical care system, so it is up to individuals to keep as healthy as possible, and that includes mentally alert.
"I don't think that old people want to be young again necessarily," he said. "They are experienced and wise and, I think, simply want to be healthy and to have a meaningful life."
Life expectancy figures have increased dramatically in Japan in the last 80 years.
In 1935, people could expect to reach the age of 45 but today, women live on average until 85 and men to 78. The number of people reaching 100 has doubled in the past five years and now stands at more than 20,000.
"I'm not sure how well this game will sell overseas, especially as the studies are incomplete and the scientific evidence is still lacking"
Tokyo Metropolitan Institute of Gerontology
But Suzuki also believes that Japan's elderly population are equally as susceptible to fads or fashions as the nation's famously fickle teenagers.
"It is in the nature of Japanese people to be uniform, so I think that when older people hear about something like this then they believe they have to do the same thing," he said.
"They are told that it's good for them to exercise their brains, they believe it and it becomes a trend.
"People in Europe place more emphasis on individuality and I'm not sure how well this game will sell overseas, especially as the studies are incomplete and the scientific evidence is still lacking."