OSAKA - A vacant house in Osaka's Ikuno Ward collapsed in October after standing empty for more than a decade, exposing a loophole in Japan's vacant home legislation that prevents authorities from taking action against deteriorating properties when they form part of a row of connected houses still occupied by other residents.
The wooden house collapsed on October 4, scattering debris across the surrounding area and forcing authorities to close a nearby road for approximately a week. Four days later, the remaining third-floor structure also gave way, causing further alarm among residents who had repeatedly warned local officials about the danger.
"It made an incredible noise, a rattling sound unlike anything normal," one resident recalled. Another expressed frustration that warnings had gone unheeded, saying neighbors had been reporting the problem for years.
According to local residents, the property had been unoccupied for more than 10 years. Several people had contacted the ward office on multiple occasions, but officials had done little beyond inspecting the site. Despite the obvious deterioration, the city maintained that it had been unable to take stronger action under existing legislation.
The problem centers on Japan's Act on Special Measures Concerning Vacant Houses, commonly known as the Vacant Houses Act, which allows municipalities to order repairs or demolition of dangerous abandoned properties and, in certain circumstances, carry out demolition themselves through administrative enforcement.
However, the legislation generally applies to buildings that are entirely unoccupied. In the case of traditional Japanese row houses, known as nagaya, several separate residences share structural elements and are legally treated as a single building. Even when individual units have been abandoned, the entire structure may fall outside the law's definition of a vacant house as long as someone continues living in another unit.
The property that collapsed in Ikuno Ward was one of four connected residences, with the other three still occupied. Because the building as a whole was not legally classified as vacant, Osaka City officials said they could not invoke the Vacant Houses Act to investigate ownership more extensively or require corrective measures.
"We received reports and inspected the site, but because people were living in the other three residences, the Vacant Houses Act could not be applied, and we were unable to conduct a more detailed investigation of the owner," a city official explained.
The problem extends beyond the collapsed property. Near JR Momodani Station in the same ward, another deteriorating building stands along a school route, with sections of its exterior walls missing and parts of the second and third floors exposed. Despite concerns about the danger to pedestrians and schoolchildren, the property has remained untouched.
Japan's growing number of vacant homes has made such cases an increasingly serious concern. A national survey conducted in 2023 found a record 9 million vacant dwellings, reflecting the effects of an aging population, declining household numbers and difficulties surrounding property inheritance.
Osaka is particularly vulnerable because of its large stock of traditional row houses. Ikuno Ward has the city's second-highest number of vacant homes, while older residential neighborhoods in southern Osaka contain extensive concentrations of aging connected properties.
A real estate company in Higashisumiyoshi Ward demonstrated the challenges involved in maintaining and disposing of these buildings through a 57-year-old row house measuring approximately 50 square meters across two floors.
The property had previously been occupied by a woman in her 90s who moved into a care facility about two years earlier and subsequently died. Because she had arranged for a lawyer to handle her estate, the property could be purchased by a real estate company before falling into serious disrepair.
Such relatively straightforward cases are not always possible.
A real estate professional explained that aging row houses frequently suffer from rotten flooring around bathrooms, termite damage and leaks caused by deteriorating waterproofing on balconies. Many vacant units are 40 to 50 years old, and without regular maintenance their condition can deteriorate rapidly.
Demolition also presents complications because neighboring homes often share structural supports.
"The pillars are shared with the neighboring property, and the boundary runs through the center of the pillar. That is a characteristic of row houses," the real estate professional explained. "It is possible to demolish one unit, but you need permission from the neighbors, and you also have to repair the exposed walls afterward."
These structural and legal difficulties can leave owners unable to sell or demolish properties they have inherited.
The company receives approximately 200 consultations a year from owners facing such problems, particularly in southern Osaka wards including Nishinari and Higashisumiyoshi. With increasing numbers of people having no heirs or choosing to renounce their inheritance, industry professionals expect the number of abandoned row houses to rise further.
Osaka City has more than 30,000 residential units forming part of connected row-house buildings. If unoccupied units continue to be overlooked because they do not meet the legal definition of vacant houses, experts warn that collapses similar to the one in Ikuno Ward could become more common.
Some municipalities have begun developing their own measures to address the gap in national legislation.
Ikeda City in Osaka Prefecture introduced an ordinance in 2020 covering the appropriate management of vacant buildings and vacant row-house units. Unlike the national law, the ordinance allows municipal officials to investigate individual unoccupied units within connected buildings and provide advice or guidance to their owners.
Over the six years since its introduction, the city has issued guidance in 17 cases, with owners taking steps such as demolition in nine cases, resulting in improved conditions.
Municipal officials also inspect vulnerable properties around periods of severe weather, when typhoons, heavy rain and strong winds can accelerate structural deterioration.
The ordinance goes further by allowing the city to carry out emergency measures, including removing dangerous debris, when a vacant unit presents an immediate threat.
Other municipalities in Osaka Prefecture, including Yao and Izumi, have introduced similar local ordinances, reflecting growing recognition that the national framework is insufficient for dealing with connected residential properties.
However, officials acknowledge that emergency intervention alone cannot provide a permanent solution.
Even when a municipality removes debris or takes other temporary safety measures, the underlying problem remains unless the owner carries out repairs or demolition. Without action by the property owner, authorities may be forced to repeat emergency work as the building continues to deteriorate.
An Ikeda City official suggested that more fundamental measures, including revisions to national legislation, may ultimately be necessary.
Real estate companies, lawyers and other specialists in Osaka have also begun working together to prevent vacant row houses from becoming dangerous before their condition reaches a critical stage.
A research group organized by an association of real estate businesses in Osaka Prefecture is examining cases involving abandoned connected houses and developing practical responses to problems such as unidentified owners, inheritance disputes and insufficient funds for demolition.
Its central approach is what participants call "preventive intervention," encouraging owners and neighboring residents to seek advice and resolve ownership or maintenance issues before an entire building becomes vacant or seriously deteriorates.
The initiative, launched in July 2026, includes distributing information to row-house residents explaining the risks and available legal options. It has also been selected as a model project by the Ministry of Land, Infrastructure, Transport and Tourism, making it eligible for government subsidies.
One Osaka woman living in a four-unit row house, where the other three homes are vacant, has already benefited from the initiative.
She had repeatedly experienced rainwater leaking into her home because leaves from a large tree growing on a neighboring vacant property blocked the drainage system.
After consulting the ward office, she was connected with specialists involved in the preventive intervention program.
A judicial scrivener investigated the neighboring property and found that its owner could not be identified. The woman subsequently learned about a legal procedure allowing a court to appoint someone to manage property whose ownership is unknown, potentially making it possible for the land and building to be purchased.
"I learned that if I applied to the court and the situation was recognized, it might be possible to buy the neighboring land," she said. "It was a tremendous help because there were so many things I simply didn't understand."
A real estate company is now proceeding with the necessary arrangements to acquire the property using the legal framework for land and buildings with unknown owners.
Those involved in the project say the case demonstrates that solutions are available when residents seek professional assistance early, rather than waiting until a building becomes dangerous.
The research group hopes that wider awareness of these procedures will help prevent future disputes and deterioration, particularly in neighborhoods where elderly residents live alongside increasingly vacant properties.
Meanwhile, the aftermath of the October 4 collapse in Ikuno Ward has finally been resolved.
After the building collapsed, Osaka City was able to contact the owner, who said they had been unaware of the property's deteriorating condition until officials notified them. Demolition began in late October, and approximately a week later the dangerous structure had been removed, leaving the site cleared.
Residents expressed relief after weeks of disruption and years of anxiety.
"I hope the national government will think seriously about this," one resident said, describing the collapse as an example of the dangers posed by aging residential buildings.
Another welcomed the return to normal life after the demolition, saying the neighborhood could finally put the ordeal behind it.
The incident has highlighted a broader problem facing Japan as its population ages and more homes fall vacant. Traditional row houses, once an important feature of densely populated urban neighborhoods, can leave individual owners and residents trapped between shared structural responsibilities, complicated property rights and legislation that fails to recognize partially abandoned buildings.
With local governments increasingly forced to devise their own solutions, the collapse in Ikuno Ward has renewed questions about whether national legislation needs to be revised before further deterioration leads to injuries or more serious disasters.
