In a 2005 interview with the game's producer Koji Igarashi published in the official Konami strategy guide, he chose the theme of "revenge" for this game, because the Belmonts had been seen as the good guys up to that point, and he thought it would be nice to try something other than a moralistic "good triumphs over evil" theme sometime. Another reason why was that Castlevania still had "an excellent world for telling a "dark hero" story", with Alucard being an example of this even though he's still considered somewhat good since he is fighting for the just cause of stopping Dracula. For Castlevania: Curse of Darkness however, he wanted the motivation itself to be impure, so he came up with the theme of revenge, and then he thought it could be a lot more interesting if each side was out for revenge against each other.

According to a 2005 interview with the game's producer Koji Igarashi published in the official Konami strategy guide, he stated that the decision to set the game three years after the events of Castlevania III: Dracula's Curse was significantly driven by his love for the game. The introduction of the "Innocent Devil" system, where players have a demon servant fighting alongside them, prompted him to consider the game's placement within the Castlevania timeline. Given the demonic nature of the Innocent Devils, Igarashi decided the story should align closely with that theme.

The idea he came up with back then revolved around a hidden narrative during Ralph C. Belmont's battle against Dracula, where there existed someone who betrayed Dracula, and another individual who relentlessly pursued this traitor. Igarashi believed that despite these circumstances not being part of the officially recorded history in-universe, they still significantly impacted Dracula’s defeat, and in that sense the gameplay system came first and the story was woven around it,

In a 2005 interview with the game's producer Koji Igarashi published in the official Konami strategy guide, he explained the decision to change the series' title in the domestic Japanese market from "Castlevania" back to "Akumajo Dracula".

The title change to Castlevania in Japan initially occurred because the Akumajo Dracula games enjoyed a larger market share in Europe and America compared to Japan. Consequently, more reports and information about the games were available in those regions, and they were released there first. In the recent past, news from outside Japan was harder to access, but with the advent of the internet, Japanese users could now easily stay informed. However, there was a concern that Japanese players might not immediately recognize the equivalence between Castlevania and Akumajo Dracula, so the main title of the previous game Lament of Innocence was changed to Castlevania in Japan to address this.

Subsequently, for Curse of Darkness, the decision was made to revert to the original title because the team felt that the Castlevania name had become associated with trilogies, inadvertently making it challenging for fans to find information about the Akumajo Dracula titles. The team wanted to ensure clarity for Japanese fans and clear up any confusion among Akumajo Dracula fans about if Castlevania was supposed to be Akumajo Dracula.