KOBE—The horrific killing of a woman at her apartment building here has underscored the chilling reality that a simple age-old trick can allow sinister people to bypass modern security systems.

The suspect is believed to have followed the 24-year-old woman to the building’s entrance and then slipped inside before the automatic security lock system could close the door.

The intrusion stunned the real estate industry, which has touted the security of auto-lock systems in advertisements for their properties.

At least one security company now plans to upgrade its system to prevent unwanted visitors from entering the premises.

SLIPPED IN 

The crime occurred at around 7:20 p.m. on Aug. 20 in Kobe’s Chuo Ward.

Security camera footage shows a man who looks like Masashi Tanimoto, the 35-year-old suspect, closely following the woman into the building just after she opened the auto-lock entrance door.

She died after being repeatedly stabbed with a knife in the upper body in the elevator, Hyogo prefectural police said.

In a separate case, a South Korean woman was fatally slashed in the neck in Tokyo’s Setagaya Ward on Sept. 1. The suspect, the victim’s boyfriend from South Korea, is believed to have intruded into her apartment building two days earlier by sneaking in behind another resident who had opened the door.

“The Kobe case was so shocking,” said a salesman with a real estate agent with branches across Japan.

A search for “well-secured” properties on the listings page of his employer’s website shows places equipped with an auto-lock system and an intercom with a monitor.

Residents open auto-lock doors with a key, a personal identification number or other means. They close soon after the person enters.

The internal affairs ministry’s 2023 Housing and Land Survey showed that 21.5 percent of all apartment houses built between 1981 and 1990 were equipped with an auto-lock system.

The proportion rose to 46.4 percent for those built between 1991 and 2000 and to more than 60 percent for those built more recently.

Overall, 44.2 percent of all apartment houses in Japan are equipped with an auto-lock security system, according to the survey.

A representative of security firm Sunnobel Co. gave a rough personal estimate that 80 percent of all people likely consider auto-lock systems as a requirement for their residences.

Sunnobel, based in Osaka’s Nishi Ward, is urging its customers to introduce auto-lock systems.

“Auto-lock can be an added value that will help improve occupancy rates,” the representative said.

But the official acknowledged that concerns about outsiders slipping through auto-lock systems are certainly shared across the industry.

The representative said combining an auto-lock system with a surveillance camera and a mirror could improve the security performance.

Hideo Kakinuma, a vice president with Zenkanren (National federation of apartment building residents’ associations), a nonprofit based in Tokyo’s Chiyoda Ward, views things differently.

“Just because an apartment house has an auto-lock system doesn’t mean it is safe,” Kakinuma said. “Slipping in behind others is an old problem. Residents’ associations should organize study sessions on security measures to change the awareness of the residents.”

The Kobe stabbing has prompted Tokai Security, a security equipment company based in the city’s Nagata Ward, to consider a significant upgrade.

Company officials said they are thinking about removing an auto-lock system from an apartment building and replacing it with a security gate designed to let in only one person at a time, like an automatic ticket gate at a train station.

The proposal, still in the planning stage, would also include security sensors installed at the gate. If the sensors detect passage of more than one person, a siren will be sounded, a lamp will be lit, and an email will be sent to the security guard office and other recipients, the officials said.

“You can carry a tear-gas spray to protect yourself, but it may not help you fight off a would-be assailant,” Tokai Security President Tatsuji Asai said. “The key point lies in designing a system that will deter those who may attempt to do harm.”

Asai said the company’s proposed upgrade would cost about 10 million yen ($68,000) to install in an existing apartment house. He said he hopes the gates will be a part of construction of new apartment buildings.

The work would certainly weigh financially on the residents, but “life matters more than anything else,” Asai said.