Saitama police arrest two men for car thefts using hula hoop antennas

Two men, including 28-year-old Masatomo Saito, have been arrested by Saitama Prefectural Police on suspicion of stealing two vehicles in Saitama Prefecture using a method known as a ‘relay attack.’

The suspects allegedly used a makeshift device consisting of a hula hoop wrapped with wire and cord to serve as a large loop antenna. This device was used to intercept and amplify the weak radio signals emitted by electronic smart keys, tricking the vehicles into believing the key was nearby. This allowed the suspects to unlock the doors and start the engines.

Police believe the duo may have been involved in dozens of similar thefts between February and March 2026 in Saitama City and Ina Town. Experts note that while the use of a hula hoop as an antenna frame is unusual, the relay attack method is a known technique used internationally to bypass electronic security systems.