Twelve senior officials who each adopt an animal of the Chinese zodiac — a numbered set borrowed wholesale from a calendar.
Filed by its count, not its title
Reduced as a phrase, “The Zodiacs” would sit on The Signal — but that would be reducing wording this reference chose. The set is filed under 3 · The Telling instead, because 12 is what its author chose, and a chosen number outranks an imposed one.
What it is
Twelve high-ranking members of the Hunter Association, each associated with one animal of the Chinese zodiac and each dressing, to varying degrees of enthusiasm, in accordance with it.
What the number does
Borrowing a number that already exists is the cheapest possible way to make an organisation feel old. Nobody needs to be told why there are twelve; the reader supplies the reason from a calendar they already know. That inherited weight is doing work no invented number could.
It is also self-limiting in a useful way. A zodiac cannot be extended — there is no thirteenth animal — so the author is protected from the inflation that eventually afflicts a ranked set like the Espada, which had to invent a zero to keep climbing.
The zodiac as a manga habit
The twelve animals are among the most reused numbered sets in the medium, and the reuse ranges from the structural to the decorative. It is a set that arrives pre-assembled with names, personalities and an order, which is a large amount of free material for a number that costs an author nothing to adopt.