It was Japan's first hanging since Takahiro Shiraishi, the "Twitter killer" who murdered and dismembered nine people, was put to death in June 2025.
Sunao Takami, the man reportedly executed on Friday, doused a pachinko parlour in Osaka near his home with gasoline and set it on fire, killing four customers and one employee.
The justice ministry declined to comment.
Japan and the United States are the only two G7 countries to still use capital punishment, and surveys suggest there is strong support among the Japanese public.
However, there is widespread criticism of the system, with death row inmates typically only informed on the morning of their last day that they are about to be hanged.
There was one execution in 2022, three in 2021, three in 2019 and 15 in 2018, the justice ministry told AFP last year.
