TOKYO >> When Hiromi Otsuzuki joined the Japanese software company Isana.net as human resources manager four years ago, she was the only part-time employee.

Working just 15 hours a week so she could care for her stepson made Otsuzuki an outcast in a country that is notorious for the long hours office workers spend at their desks.

Her colleagues called her “part-no obasan,” or part-time auntie. Despite being a specialist, she was asked to organize bags for recycling.

“Within the company, nobody would accept me,” Otsuzuki, 48, said.

Things are better now. She is no longer the only part-time worker in the office, and she has been promoted.

Judging by the numbers, things are looking up for other mothers in the Japanese workforce. According to a government survey released in July, nearly 71 percent of women with children were working, as of Japan’s most recent fiscal year, which ended in March. That is the highest level on record, and a 14-percentage-point increase since 2004.

But the figures mask some major problems with the quality of work available to working mothers.

Opting for part-time work

Under pressure at home to maintain their child-rearing responsibilities, many professionally minded mothers are opting for part-time work.

In Japan, that means accepting meager benefits, little job security, few opportunities for advancement and pay that is often so low that women’s rights advocates have described it as exploitation.

Only 1 in 4 mothers in Japan was employed full time in the last fiscal year.

“Every company thinks that opening doors and hiring women is the end goal,” said Kaori Sasaki, head of the Committee for the International Conference for Women in Business. “But actually, that is the starting point.”

After graduating from a junior college in 1992, Otsuzuki spent 19 years in jobs that included secretary and human resources staff member, mostly at the electronics giant Sony and NHK, the national broadcaster.

In 2011, she married a man who had a 10-year-old son, and she felt obligated to leave her career and care for the boy.

She found life at home more stressful than being at work, and after three years she decided to find a job.

“In Japan, housewives have very high expectation from society and mothers-in-law,” she said. “It was too much pressure.”

Finding a suitable position proved to be harder than she had anticipated.

“Companies don’t value experience, because they have their own way of doing things,” she said. “I had to act like a freshman.”

Managers who showed an interest in hiring her also insisted that she work full time. But with the continuing tug of household responsibilities, Otsuzuki preferred fewer and more flexible hours.

It took Otsuzuki six months to land the position at Isana.net, with an initial hourly wage that was about 40 percent of what she had earned in her last full-time job.

Although Otsuzuki has managed to strike a balance between home and office, many other working mothers find that the pull between the two makes it difficult for them to stay in jobs.

After she had her second child, in 2013, Misa Masuo, a longtime employee of the cosmetics company Shiseido, moved into a position as a saleswoman in a department store that allowed her to work fewer hours. Two years later, she resigned, overwhelmed by her dual duties.

At home, she was what is known in Japan as “one-ope child care,” or one-person operation. She was expected to go home after work and cook, clean and bathe the children — a task she describes as “always chaotic” — entirely on her own.

Masuo’s husband, a chef, worked long hours at a restaurant and did little to help with the children beyond ushering them to day care each morning.

At work, Masuo, 39, felt a constant sense of guilt that she was imposing extra responsibilities on her fellow saleswomen, especially during busy shopping hours.

“I was always saying ‘I’m sorry, I’m sorry’ to colleagues, as I dashed home from work early,” she recalled.

Such challenges frequently derail women’s careers and contribute to a gender pay gap that is the third biggest among the Organization for Economic Cooperation and Development’s member countries, behind only South Korea and Estonia.

“The quality of jobs given to women is not that high,” said Machiko Osawa, director of the Research Institute for Women and Careers at Japan Women’s University. “That has to be improved. Then not only are women working but they contribute more.”

Severe economic pressures are forcing some change. Managers are experiencing labor shortages amid low unemployment and an aging labor force, making them more willing to accommodate working mothers.

Campaign for women

Prime Minister Shinzo Abe has also made the inclusion of women in the workplace part of his campaign to revive Japan’s long-stagnant economy.

He has promised better access to child care, and Parliament has introduced legislation that would require large companies to publicly state their goals for hiring women.

“A lot of companies are desperate for workers,” said Ichiro Masumura, president of BStyle, an employment agency based in Tokyo that specializes in placing female workers in jobs, including through its website, “shufu-job.jp,” which translates to housewife-job.

Advocates for women, however, contend that more needs to be done.

Tougher laws that promote gender equality in the workplace are necessary, they argue, and better training is required to sensitize male executives to the needs of their female staff members.

Since hiring Otsuzuki, Isana.net has built a team of eight mothers who work part time — out of about 45 workers in total. Otsuzuki’s status has improved, too.

This year, she received a promotion and a pay raise that nearly doubled her hourly income. Even though she still works part time, she gets the same benefits as full-time employees.

Isana Ishitani, who founded Isana.net in 2001, now allows employees to bring their children to the office if necessary and to switch between full- and part-time hours to care for children or, as is increasingly the case, older parents.

“We want the employees to work for our company until they retire,” he said. “This is an old Japanese idea. In order to do that, people need to adapt to a lot of things in their lives.”

In the meantime, Otsuzuki said, the rest of Japan has no choice but to include people like her.

“Luckily, Japan is so short of workers,” she said, “that even ‘part-no obasan’ are welcome.”