I like your Halloween haiku! Yeah, a decade ago, people in Japan had no idea about Halloween trick-or-treating, just like you said. I had to arrange visits with my acquaintances in advance so we wouldn’t surprise them when we went trick-or-treating.

When I was young, we had a very similar event during summer around Obon. We carried lanterns and said, “おかしをくれなきゃ、かっちゃくぞ、ひっかくぞ！” (“Give us sweets or we’ll scratch you!”).
Nowadays, cosplayers never miss the chance to dress up for Halloween in Japan, right? Sometimes even more enthusiastically than kids! I also love watching the Kyoto Yokai Festival video!
https://www.toei-eigamura.com/yokai/