Mostly a PSP focused interview, but Igarashi does say a bit about the Castlevania series in general. A portion of a Joystiq interview with the dracula head honcho himself...

J: Okay, so tell us about your involvement with The Dracula X Chronicles and the Castlevania series.

I: I oversee everything for the game and the series, and I also wrote the scenario and the concept document for the game. I've also worked on every Castlevania game since Castlevania: Symphony of the Night.

J: The Castlevania series has been around for a long time. Is it challenging to keep it fresh and exciting?

I: Every time I make sure to have elements from previous games, and to add new elements so each franchise seems fresh and exciting.

Full interview here