Overview
- The operating company's current president told investigators he urged switching the sauna door to a push-to-open design, which the former owner rejected over concerns about losing airtightness and heat.
- Police confirmed a previous incident last spring in another room where the interior knob detached and a customer was briefly trapped before someone outside opened the door, with no injuries reported.
- Investigators believe the couple in their 30s were trapped when an L‑shaped wooden interior knob came off during the December 15 fire, and the in-room emergency button had no power.
- Reporting indicates the sauna room was originally designed for a push-type door, yet an L‑shaped knob was already installed when the current operator took over in December 2024 after repeated wobbling and repairs.
- The Tokyo Metropolitan Police Department’s Investigation Division 1 is examining potential professional negligence resulting in death, and no charges have been announced.