On that note, I wonder how my Ph.D. applications would look if I proposed a series of doujin games and their associated fan media empire as a research topic.

There canon and fanon are more or less useless terms. Doujins have more characterizing power than the actual games more often than not. etc.

I still haven’t figured out what sense or nonsense to make out of this phaenomenon, really, which is why my comments are so devoid in anything wortwhile.

I always forget about that blood type profiling. Still, if it were something we’d more readily recognize in the west, such as astrological sign (another use for the birthday I guess…me and Kiritsugu are rocking the Scorpio), I’d be inclined to call it extraneous anyway. But then I have my priorities as a reader; I like to see neat categorizations like that handily broken (which, granted, might work better if I know which categorizations exist to be broken).

I just think it’s interesting that, in some cases, this sort of information comes from all manner of material beyond the text (granting that a light novel illustration is a part of its text, so the Fate/Zero case is a little different), and it ends up working its way into readers’ understanding of the text anyway. That broad permissiveness stands out in many of the fandoms of things I like.

And as Owen noted, Remembrance day. You can also do all manner of funky things with Japanese birthdays, they can be small puns in and of themselves.

But then I think you’re probably mostly right in it being for the trivia-obsessed otaku. A step above their obsession with giving out B-W-H measurements, at least.