Actually I think it's cannon that Sakuya was a Vampire hunter before she moved into the Scarlet Devil Mansion. But she was defeated by Remilia and as punishment, became the head maid.
Akyuu said: According to one theory, she was a vampire hunter from the outside world or another world (*4), and followed the vampires into the Scarlet Devil Mansion to try to slay them, but was defeated instead.
Also there are many theories such as ones suggesting she is actually a Homunculus, a zombie or simply just an eccentric, but the most widely believed theory is the vampire hunter theory detailed above.
That's from Perfect Memento, so while it's not solid evidence, it's as close as you're going to get.
Tacia said: Actually I think it's cannon that Sakuya was a Vampire hunter before she moved into the Scarlet Devil Mansion. But she was defeated by Remilia and as punishment, became the head maid.
Tacia said: That's from Perfect Memento, so while it's not solid evidence, it's as close as you're going to get.
Here's the thing, though. That's a theory. It's not true or false until proven as such. Don't claim it as canon until something out-right proves the theory true, or I'll load your ass into a "canon" and fire you into the sun.