Simon was able to defeat Dracula in the first Castlevania, but not without a price. Dracula set a curse on Simon, and the only way to lift the curse is to find Dracula's body parts and burn them.
A bit different from the first game, as this time you're free to roam around wherever you please, as opposed to just going from one side of the screen to the other. You'll have to find your way through many similar looking towns and swamps, in order to find each of the five castles that contain Dracula's different body parts. The game will actually shift between night and day, so be sure to get as much done as you can during the daylight hours. When darkness falls, it will be a horrible night to have a curse indeed. You won't be able to escape from the wrath of Dracula's minions even in the towns. Luckily this time around, Simon will be able to buy better and stronger whips, such as the chain whip and Morningstar. If you're able to battle through each of the five castles, then prepare to enter one last castle, triggering a battle with Dracula himself.
This game is also known as Dracula 2: Noroi no Fuuin in Japan.