Far to the north of BomberMan's hometown, Peace Town, lies the modern metropolis Diamond City. There, the evil Carat Diamond and his cohort, scientist Dr. Mook, are holding a Robot Tournament with robots specially designed for their combat and offensive capabilities. Hoping to steal BomberMan's advanced combat capabilities, Diamond has created a fake BomberMan to go to Peace Town and kidnap the real BomberMan. Aware of Diamond's plot, Black BomberMan heads out alone to face the fake BomberMan. But Black BomberMan is defeated and his castle is taken. Somehow Black BomberMan escapes and seeks refuge with White BomberMan, and warns him of Diamond's evil plan. Soon, wave upon wave of enemy robots begin their advance toward Peace Town. Now our two heroes must join forces to overthrow the evil Diamond.