Among the oldest demographic, some 78 per cent of women in their 50s said they were in sexless or very nearly sexless marriages, along with 81 per cent of men in the same age bracket.

But 57 per cent of respondents who said they were in sexless or virtually sexless marriages also revealed that their relationship with their spouse was either good or very good.

The Raison d’être study did not examine the reasons married couples in Japan are not having sex, but repeated studies by the Japan Family Planning Association over the last 20 years have shed light on the issue, Kitamura said.

In its first study in 2004, the association determined that 31.9 per cent of married couples were not having sex, with the figure rising yearly until 2020, the most recent survey, when it hit 51.9 per cent. The association’s research was affected by the coronavirus in 2022, but its latest research will be published in March and is expected to show a further increase in sexlessness.

According to Kitamura’s research at the JFPA, 22.3 per cent of women across Japan did not have sex on the grounds that it was “bothersome”, while slightly over 20 per cent did not feel like having physical contact with their husband after having a baby. Another 17.4 per cent said they were too tired from work, while 8.2 per cent no longer saw their husbands as a sexual partner but as “family”. Other reasons women gave included being pregnant or disinterest.

Among men, the most common reason, with 35.2 per cent of the total, was that they were too weary after work. Another 12.8 per cent said they saw their wife as “family” instead of a sexual partner, and 12 per cent had lost interest in sex after a child was born. Just 7.2 per cent did not have sex because it was “bothersome”.

Tokyo-based Amie, a woman in her late 30s who spoke under a pseudonym like many of the women interviewed by This Week In Asia, says there are several reasons for her marriage lacking in physical love, but a lot of it came down to simply being tired.

“My husband has a very physically demanding job, and he works at different times of the day and night, so it is difficult to have a regular routine,” she explained.

“It was different when we were younger and when we were trying to have a baby, but that did not happen, so we just sort of stopped,” she said. “I work part-time as well, and there just never seems to be a ‘good time’ for us.”

Keiko, who is in her late 40s, said she and her husband have “drifted apart” and lead largely separate lives since their daughter moved out. And as they appear to have so little in common nowadays, Keiko is contemplating a divorce.

Maya, who is in her 40s and lives in Kanagawa Prefecture, had a healthy sex life with her husband through their 30s, she said, but that changed when she discovered that he had been having an affair.

“Things were difficult for a couple of years, of course, but we have a daughter and we both believed it was important for us to stay together for her,” she said. “As time has gone by things have got better, but we are not back to how we were before, and our relationship is less physical than it used to be.”

For Tokyo-based Taka who is in his late 40s, the survey’s finding that post-work weariness killed libido rang true.

“I work long hours and I’m often away from home during the week. When I do get home it’s late and I’m tired, so all I want to do is have a bath and get to bed,” he said. “I think it is the same situation at many Japanese companies. And then at the weekend I try to do things with the children, so there is never enough time.”

02:18

Japan’s greying population: 1 in 10 now 80 or older as country’s birth rate continues to fall

Japan’s greying population: 1 in 10 now 80 or older as country’s birth rate continues to fall

Kitamura says his research supports the theory that many people are simply putting in too many hours at their companies and have no energy for anything else when they do get home. On top of that, there are worsening financial pressures on most couples.

“There are many pressures on Japanese people today, the most fundamental of which is their relative lack of money to go out to drink or to a restaurant with a partner,” he said. “In Japan, it is difficult to fall in love if you are poor.

“Among young people, we also see that many have poor communication skills,” he said. “If people are reluctant to communicate with the opposite sex, or if they cannot maintain a positive attitude towards sex, then the sexless trend will increase further. It is difficult to break out of this cycle.”

And that, he warns, bodes ill for a population that is already in clear decline, with the 123.29 million Japanese last year, down from a peak of 128.1 million in 2010 and predicted to contract to 104.69 million in 2050.

“Japan’s declining birth rate is even more serious than the sexless population,” Kitamura said. “Young people are not getting married; how can we build a society in which it is easier for impoverished young people to get married? There is a mountain of issues to be addressed, such as how the government can provide couples with financial support and the different perceptions between men and women of the benefits of marriage.”