Although it wasn't just the costume, it was also the whole effect that I enjoyed. I had managed to get into the school without being noticed by any of the students. Since they had no idea that I had planned on coming, I decided to make it a surprise and stayed out of sight until the trick or treating. (I hid in the women's staff change room between classes and during cleaning time.)
The room I was in has two entrances, one with a single door (on the right) and one with double doors (on the left). There's a sink near the double doors and next to the sink is a bit of a column so you can't actually see the door on the right without going further into the room and then looking back. So anyway, I closed the curtains and locked up the single door and put newspapers up over the window. I put the candy on a back shelf--clearly visible from the double doors, which I left open. Then I hid in the little alcove by the single door.
At first I was worried that students wouldn't come in--a couple did pass by when they didn't immediately see a teacher, even though the candy was visible and the door was open!--but eventually a couple of boys came in and started heading towards the candy. And that's when...
The best reaction I got was from a third year boy. He had heard that I was in the room, but he didn't know where. Near the open doors there was a broom closet (to the left--so the opposite direction from where I was hiding). He was clearly all psyched up and expecting to see me pop out from there when he threw open the door. Consequently, he was totally unprepared to have me come up from behind him. He literally jumped and screamed! Totally hilarious. I really wish I had a video of that moment!
Even after students knew it was me, they still cringed back when I came at them with my Sadako pose (as pictured above). =P It was great.
Although I gave up watching the mask contest to keep the element of surprise, it was totally worth it. Probably my most fun Halloween at Kirita ever!
I only wish the event had taken place a little later so it would've been darker...Although I guess students might not have dared come into the classroom if it had been too dark, so it was probably for the best.
Bonus: Photos from the previous night's Sadako practice session!