During the night of the 31st, a number of Kiseki natives (dressed up in elaborate costumes) will be going around the city and rooms for trick-or-treating! It should be clear now why Kiseki has so kindly provided everyone with plenty of candy to spare, right?
And well, if your characters didn't happen to stock up on it, or buy their own, they'll end up being tricked; and it just so happens that Kiseki's magic will be aiding the natives on their pranks!
( TL;DR ahead )
These events will keep occurring up until Monday. Most things should wear off after a while, as usual, but you can bother your characters for longer, if you want. And, as you should already know, feel free to ask any questions!