On August 6 at 3:35 p.m., the boy, an 18-year-old from Yokohama, and Mieko Kumao assaulted the driver, 63, in the face and head with a bottle and stole his wallet and vehicle (valued at 900,000 yen) along National Route 399.
The boy, who has been charged with assault and robbery, admits to the allegations, officers from the Kita Police Station said.
The injuries to the driver are expected to require one month to heal.
After the incident, the suspects fled the scene. According to police, the pair had planned to commit suicide together and were using the stolen vehicle to find a location.