Originally Posted by
Petrikow
Japanese reading aid. I'm actually not sure where the appellation comes from, but what we call "ruby" is what is in Japanese called Furigana.
Furigana is ostensibly used as a way of showing the reading of a certain combination of characters (in the form of the reading, i.e. the pronunciation being shown above the word), because the writer suspects that the reader could have trouble reading them otherwise. Or perhaps they are trying to insist on one reading over the other. These days, you see it fairly commonly used in manga aimed at a younger audience, who have yet to learn all the Kanji required to otherwise read that manga.
Yet this feature of furigana is not particularly important in something adult-oriented like Tsukihime. Indeed, for a lot of works like this, it has become a fad to use Furigana to sort of show-off a non-intended reading of a word. An example would be using 暗黒 (lit, darkness) with the furigana ダークネス (Japanese transliteration of the English word "darkness") instead of the usual reading of that word as あんこく. You can extend this to just show any kind of double-meaning to any word, to the point where the original purpose of furigana becomes quite muddled.
This is indeed where we end up when we read things in Nasu-land. This is why the word 代行者 (lit, agent) is translated as Executor, because the furigana for the word is consistently listed as エクスキューター (Japanese transliteration of the English word "executor"). Sometimes he goes even more overboard, and replaces whole sentences worth of words with some furigana. Of course, this is a technique not only Nasu employs, but is rather common among genre writers in Japan. Though I will say, Nasu may be one of the most rampant abusers of Furigana around.