Roughly, what would "Shikkoku Taru Zensoukyoku" translate to without the pronunciation key?
So, even though the subtitle is Japanese, the pronunciation key says it should be said "Dark Night Prelude" in English? Fascinating. o.o Makes me wonder, though, how someone not-in-the-know would know to pronounce it that way if he or she were to see the title in text without the pronunciation key (that is, written 悪魔城ドラキュラ漆黒たる前奏曲 without ダークナイト プレリュード written above/below or alongside it), unlike with the logo where it's right there under the kanji.
My Castlevania geek knowledge, I feel it increasing.