Tiny Shirogane post office in a quiet Tokyo neighborhood, with just three clerks and one ATM, might seem far removed from the world of global finance.
But when Japan Post is privatized on Monday, the Shirogane office will become part of the world's biggest commercial bank - with assets of 349.82 trillion yen (US$3.03 trillion, EUR2.14 trillion) - in a move intended to inject competition into Japan's banking sector.
"Our customers will soon experience the merits of privatization," Yoshifumi Nishikawa, president of Japan Post, said Friday at his final press conference before the reforms kick in. "They will see a better quality of services, or new products - in short, more convenience."
The massive changeover is the result of 2005 reforms instituted by then-Prime Minister Junichiro Koizumi, a former post and telecommunications minister who championed the issue in his landslide elections victory that year.
Much more is at stake than just stamps and letter deliveries: Japan Post operates a bank with more than 400 million accounts. Its 24,500 offices nationwide act as sales agents for insurance and investment products.
For millions of rural Japanese, the post office is their only bank, and the system's ubiquitousness has made it a symbol of a benevolent government ready to cater to every citizen's needs.
"The post office is such a basic necessity," said Kazuko Nishina, 36, an accounting clerk, who was withdrawing cash from her savings account at the Shirogane post office.
"I'm still not sure what's going to happen with privatization, but I hope there aren't any surprises for ordinary customers," she said.
Changing such an entrenched system has been tough. When Koizumi pushed through the reforms in 2005, critics warned privatization would reduce services, especially to the countryside. Even lawmakers within his own ruling party vilified the reforms as another attack by modern times on an orderly, secure society.
But Koizumi argued the government guarantee on postal savings had encouraged generations of Japanese to park their money in the low-interest accounts, creating a stagnant pool of savings and diverting funds away from more productive investments such as stocks and mutual funds.
Experts have also said that postal funds have been used to finance pointless government-backed public works projects - bridges to nowhere, redundant roads - and to purchase government bonds, contributing to a public debt now more than 160 percent of Japan's gross domestic product.
"These reforms were necessary in terms of making more efficient use of funds," said Kentaro Kogi, banking analyst at Macquarie Securities.
Privatization could also help foreign banks and investment companies scoop up new clients, with the huge savings pool up for grabs at a time when more Japanese are turning to stocks and mutual funds.
That means big money for both domestic and foreign banks, as well as insurance companies.
"We can expect the changes to be a plus for stock markets, against the general backdrop of a trend toward more diverse investments," Kogi said.
The entity privatized on Monday will eclipse Citigroup, with assets of $2.22 trillion (EUR1.57 trillion), as the world's largest commercial bank. Third will be Japan's Mitsubishi UFJ Financial Group, with $1.67 trillion (EUR1.18 trillion).
Under the 10-year privatization plan, Japan Post will be broken into four separate businesses, initially held under a government-controlled holding company: an insurance company, savings bank, mail courier and post office management firm.
The companies will be made independent by 2017 and listed on stock markets. The new bank hopes to improve returns on its savings by starting mortgage and credit card businesses and lending to small companies.
Still, uncertainties remain.
Some say far from encouraging open competition, Japan Post will be allowed to encroach on rivals by introducing new investment services and new insurance products before a more level playing field is created.
Another issue is whether foreign firms will have equal footing to sell investment products through the newly privatized bank. So far, they have been granted only a minor role, with Goldman Sachs Asset Management the only foreign firm chosen from a dozen that applied to sell their funds.
Some analysts say the mammoth organization - largely lacking expertise in more sophisticated investments - could struggle to stay profitable. That raises the risk the bank could start selling off its huge government bond holdings, causing a hike in yield and ultimately adding to the government's debt payments.
"The concept of postal privatization is good. It will inject competition into the banking sector and raise the overall quality of financial institutions, and would encourage more risk-taking behavior and revitalize the economy," said Junsuke Senoguchi, a banking analyst at Lehman Brothers Japan. "But, depending on how privatization plays out, the move could ultimately damage public finances."