Keys are special items in Bomberman Portable.
They are a total of 10 Keys and are found in some of the levels. 9 Keys are required in order to access the tenth and final world, Bagular's Spaceship and get the true ending. The additional tenth Key is only used to unlock the battle stage Searchlights. Each world hold one Key (generally found half way), and requires some conditions to make it appears, such as killing all enemies of the areas, bombing an exit, or clearing all Soft Blocks.
Once a key has been gathered in a world, it will be shown next to the location, when navigating the world map.