The defense counsel for Tomohiro Kato has appealed the death sentence handed down last week by the Tokyo District Court over the temp worker's 2008 massacre in Tokyo's Akihabara electronics shopping district.
The appeal was filed with the Tokyo High Court on Thursday.
On March 24, the Tokyo District Court convicted Tomohiro Kato, 28, of running down five pedestrians with a truck, killing three and injuring two, in a vehicle-free pedestrian zone in the district on June 8, 2008, and fatally stabbing four passersby with a dagger after getting out of the vehicle.
Kato was also found guilty of wounding eight other people.