Like many other young couples, they tried to raise their child in the city but found life among the apartment blocks too crowded and expensive, with few child care options. Eventually, they gave up.
"When people are in their 20s and 30s, they can't really afford to live in a bigger space in a city," Katsunori said. "We knew that if we wanted to have more kids, we couldn't do it there."
Fourteen years later, the Osakas moved to Nagi, where Katsunori grew up. The sleepy agricultural town in western Japan has become a success story in the country's efforts to boost its declining birth rate.
With a population of about 6,000, Nagi feels a world away from Nagoya, and residents cite the lack of busy streets and crowds as reasons why it is a great place to bring up children.
But they're not the only benefits: Nagi also pays couples who live there to have children.
Families receive a one-time 100,000 yen ($879) payment for their first child, 150,000 yen ($1,335) for their second and as much as 400,000 yen ($3,518) for the fifth child born to the same family.
Nagi has been ramping up payments since 2004, as well as offering other fertility-boosting parental perks, to turbocharge the town's birth rate and buck Japan's broader trend of aging populations.
Perks include subsidized housing, free vaccinations, school allowances and reduced nursery costs.
And they appear to be working.
In the neighborhood where the Osakas live, most couples have three or more children because they can and they want to.
This leaves Nagi in stark contrast to much of Japan.
Between 2005 and 2014, the town's fertility rate -- based on the average number of children a woman has in her lifetime -- doubled from 1.4 to 2.8, to widespread domestic acclaim.
Since then, Nagi's total fertility rate has dipped slightly to 2.39 but is still considerably higher than the national average of 1.46.
Japan has been on a steady demographic decline since the 1970s.
In 2017, fewer than 950,000 babies were born while the number of deaths rose to a postwar high of
1.3 million, according
to the Ministry of Health and Labor.
The country's total population stands at 127 million,
and children make up just 12.3% of the total, compared with 18.9% for the US, 16.8% for China and 30.8% for India, according to government figures. And by 2065
Japan's population is expected to drop to about 88 million
Tokyo, a city of
more than 9 million people, has the lowest fertility rate of all the 47 prefectures in Japan
, at 1.17
. It also has the largest number of children on waiting lists for day care facilities.
More than 5,400 children are seeking an elusive spot at day care centers in the city, nearly 30% of the national total.
Traditionally, government policies had made it difficult for working men and women to balance their careers with family life, said Hisakazu Kato, a professor of economics at Meiji University in Tokyo.
As well as a lack of child care, the country's declining fertility rate is influenced by career demands and the increasing trend among men and women to delay or avoid marriage
. The numbers of people still unmarried by age 50 hit a record 23.37% for men and 14.06% for women in 2015, according to a report
released by the National Institute of Population and Social Security Research.
But Kato said another key factor is the steady migration of people from the countryside to
expensive smaller apartments in crowded cities.
More than 93% of Japan's population lives in urban areas
, where having one or more children is just too hard for many couples.
"There's a huge gap between the cost of living in Japan's major cities and the less populated areas of the country," Kato added. Couples in the city are often also far from their families, who could otherwise help support them.