Hissatsu: Sure Death

Hissatsu Sure Death THE HISSATSU ? is a 1984 film based on the television series Hissatsu. The film is an occasionally whimsical Japanese drama about assassins.

The rogue killer is referred to as Copper in the film, a reference to the assassins gruesome calling card, which is a copper coin left in the mouth of each victim. The ultimate realization that Copper commands an army of assassins simply means that the climax involves an orgy of assassinations.

Source: Wikipedia