Couples Death in Locked Private Sauna Exposes Regulatory Failure

The blaze broke out on December 15th at a private-room sauna, killing hair salon owner Masaya Matsuda, 36, and his wife Yoko, 37, a nail technician. According to people familiar with the investigation, the emergency button inside the sauna room, intended to send an alert during emergencies, appeared to have been pressed, suggesting the trapped couple may have tried to call for help.

However, the alert should have been received by a control panel installed in the shop’s first-floor office, but the panel’s power was turned off. Although three employees were in the building at the time of the fire, the office itself was unattended.

The shop owner told the Metropolitan Police Department during voluntary questioning: "I have never turned the power on. I have never touched it."

Friends described Matsuda as a devoted family man who had become even more dedicated to his work after the birth of a child several years ago, building a well-known reputation in the beauty industry while planning further business expansion. A friend said Matsuda had mentioned strong business performance in December and suggested the sauna visit may have been a reward for himself and his wife.

During a second day of on-site inspections on December 17th, alarms echoed through the building as authorities checked the operation of fire detection systems. Firefighters previously found the couple collapsed near the sauna entrance, with Matsuda lying over his wife. Investigators noted that both the interior and exterior door knobs had come off and fallen to the floor, despite the sauna requiring the knob to be turned to exit.

An autopsy conducted by the Metropolitan Police listed the cause of death as undetermined, though investigators believe burns or hyperthermia were likely. Matsuda suffered more extensive burns than his wife, leading police to believe he may have tried to shield her from the flames.

Examination of the sauna room found several fist-sized burn marks on the wooden seating, along with burned towels. Investigators believe a towel may have come into contact with the sauna stones and ignited. Inspections also found looseness in door knobs in other rooms, raising further questions about the facility’s overall safety management. Police are considering a possible charge of professional negligence resulting in death.

The case has drawn attention to the rapid spread of private-room saunas, a trend that accelerated during the COVID-19 pandemic as demand grew for quiet, isolated bathing spaces. Operators say safety measures are essential, including emergency buttons in each room and doors designed to open simply by pushing from the inside.

At a private sauna in Funabashi, Chiba Prefecture, which has operated for three years with strong weekend demand, manager Masaki Oone said the concept of private saunas emerged during the pandemic alongside rules promoting silent bathing. He noted that the number of such facilities has increased across the prefecture, reflecting steady demand.

The Akasaka sauna obtained its operating permit in July 2022 during the pandemic, but Minato Ward officials said it was licensed under the Hotel Business Act rather than the Public Bathhouse Act. Legal experts say some operators choose the Hotel Business Act because it allows mixed bathing, which is prohibited under public bathhouse regulations.

Lawyer Ryota Kikuchi, who specializes in public bathhouse and related laws, said the choice of licensing may have been aimed at operating as a mixed-gender sauna. He also noted that under the Hotel Business Act, emergency buttons like those in question are not subject to inspection, highlighting a regulatory gap.

Kikuchi said existing ordinances did not anticipate the rise of private-room saunas and that local governments face limits in updating rules, adding that laws should be revised to reflect fire prevention and safety risks unique to such facilities.

Previously: 2 Dead in Tokyo Private Sauna Blaze

Source: TBS