I have never been able to guess what "12 days of Christmas" means. In my country Christmas is celebrated for 24 days, starting with the 1st, and culmination on the 24th of December. The two days after Christmas the 25th and the 26th are used for resting (noting at all happens these days and all shops are closed) then on the 27th the rush to pack away everything Christmasy starts, so that everything is gone in good time to celebrate the newyear
I did this series before Christmas as a lead up, but the 12 days of Christmas start on Christmas day and continue after it. If there wasn't a famous song associated with it, I doubt many people would know they exist, as only Boxing day is still part of the calendar. I'm probably not the best person to ask, as I'm not religious, but you can read about them here if you like: en.wikipedia.org/wiki/12_Days_…
do you have anyone who has an awkward radar and comes into the room as one of the seven suspect moments appears on screen (it will be the only sus moment in the entire series and they will arrive just in time to see it)
"Kurama! Take off your clothes!" When I first heard Yusuke say that (well in english he said "lose the outfit" at first I think) I blushed and thought "moron, that's not a good thing to say! Not like it'll even help! Though I don't mind if he listens...."