I had no idea.What's funny is that there is one incubus in the classic Castlevania lore but it's from an audio drama
http://castlevania.wikia.com/wiki/Magnus
But his role was to torment Maria Renard so I might give them that most of the games use male main characters so the use of a succubus makes more sense
True, given the mostly male playable characters. The exception would be Portrait of Ruin, that has a playable female character, but also only succubi.