American manual, page 2, "Story"
There is a small island on the southern sea of the planet Bomber, called "Quintet Island." Once every four years, a large-scaled Bomber Battle Festival is held on this island.
They call it the "BOMB-A-LYMPICS."
The Champion of the planet is decided for each of the five Bomber Events, and the winner is given a Sacred Golden Medal.
... Deep inside the forest of this island, you see the sight of Bomberman training hard under the waterfall.
To prepare himself for the new battle...
"When one gains all Sacred Gold Medals, a way to Master Bomberman shall open."
Believing in the ancient legend of the island, Bomberman challenges 5 Champion Teams all by himself.