Mariko is very worried for her friend because "she wants to have a baby, but has never had sex with her husband".

"Her husband just likes to play games and drink, but is not interested in sex," Mariko, 44, said of a complaint from her friend, Yoko.

Mariko herself also has no partner, though she really wants to get married and have children.

Along with the popular trend of "sexless marriage", the number of people choosing single life in Japan has also increased.

"About 25% of young Japanese will probably be single and not married for life," said Masahiro Yamada, a professor of Chua University who coined the term "single parasite" to describe Japanese people.

The number of single people in Japan has increased dramatically over the past three decades.

But is this loss of desire a cause for the low birth rate in Japan?

"Japan is really obsessed with traditional family models," said Yamada, who wrote a book about youth and conservative values.

Many young Japanese aspire to the traditional gender roles, where men are the mainstay of economics and women stay at home to take care of children and housework.

However, according to Yamada, the ideal of a traditional man as the breadwinner of the family is still appreciated.

"But for a lot of them, this ideal partner would never show up. As a result, more and more singles are coming," Yamada said.

In 2015, the University of Tokyo reported that Japan recorded an additional 2.2 million women and 1.7 million single men between the ages of 18 and 39, compared with the number of singles in 1992.

"After 30, you are either married or single. Very few people in their 30s are still unmarried and in a relationship," said Peter Ueda, an epidemiologist at the University of Tokyo.

Hence, there is reason to consider the most socially accepted adult model of adult relationships as "an obstacle to the formation of romantic relationships in Japan".

Young Japanese are replacing their sexual needs by going to sack and girl clubs, as well as maid cafes, where women dress as maids to serve men in need of sex.

Others prefer virtual intimacy, such as characters from comics, cartoons, or popular pop culture icons.

Some people do not have time for intimate relationships because the desire to make a living is greater than the desire to love, according to Yamada.

"If government policy directly addresses the situation of low-income and low-educated groups, groups that do not have a job or stable financial resources, that will make them interested in dating," said Haruka Sakamoto

In the 2015 survey, more than half of single people expressing disinterest in love said they still hope to get married at some point.