[ elizabeth touches her throat, wondering if she ought to just accept the fact she has been cursed to be a songbird for however long this lasts, and continues. singing. unfortunate. ]

Demon sacrifice, to be more accurate. A young man named Tetsuya suffered a grim fate. [ he was mad and killed wen ning. Anyway, ] It's only a theory of mine, but I believe he was purchased at an auction in old days' time. Him and two girls.

[ it's a guess that lines up with their findings at least. ]

...You'll find their written receipts within as well, not that they have much more to tell. Outside of "special goods".