Something occurred to me today and I realized that practically no one has mentioned it. We all know by now that sometimes we just randomly get items from home, usually in the strangest places, but there's something that I feel should be mentioned.
There are times where a shinki will suddenly remember something from before their death. This does not cause them to turn into ayakashi. I don't know what causes it, but one of my shinki, who is my best friend from home, woke up a few weeks ago and suddenly the day we met back home as well as several other events.
[Trying to keep this short here.]
He hasn't turned into an ayakashi with this knowledge. I don't know why he hasn't turned into an ayakashi, though I'm obviously not complaining, and since it's been a few weeks I can safely say he's unlikely to. Shinki, if you suddenly remember something, you should be okay. Gods, do not attempt to cause these memories yourself. There is something different about the shinki remembering these things on their own and us gods telling them these things. I would also assume that if Shinki A remembers something about Shinki B and tells B about it, B will turn into an ayakashi.
Anyway, if there are any shinki out there who woke up with memories they didn't have before and were panicking I hope this helps.