The men arrived at club Flower in the 5-chome district of Roppongi at approximately 3:40 a.m. and assaulted a party of five or six persons. A 31-year-old male suffered substantial head injuries and was transported to a nearby hospital, where he died an hour and 20 minutes later.
According to the Sankei Shimbun, two other members of the group received minor injuries.
Tokyo Metropolitan Police are treating the case as murder. The cause of death is believed to be internal skull damage. An autopsy will be performed on September 3.
Approximately 300 customers were on the premises at the time. One witness told police that the assailants fled by car.