The Tokyo Metropolitan Police Department on Tuesday revealed a wrist watch-type device to be worn by the so-called running police to prevent a terrorist attack during the Tokyo Marathon on Sunday.
The MPD has dispatched the running police since 2015.
Officers run the course while wearing a small camera attached to their heads, to detect terrorists who might be amid the runners.
The officers shoot a variety of footage, including areas along the marathon course.
The video is transmitted to MPD headquarters in real time.
This video can also be seen on the monitor of the new device, allowing the officers to check whether they've filmed what they want to.
On Sunday, officers including members of the MPD's mobile units, will wear the device as they run with other participants and act as security.