Well, ok, they do have a Japanese-like festival. But then again, It's not really the same japanese festival (as the festival in real life begins at the beginning of the summer, not at the end of it as the episode implies.).
Speaking of Japanese-like customs, didn't Ganondorf wear a yukata during the events of "The Legend of Zelda: The Wind Waker"? I mean, he wasn't Japanese at all (as a matter of fact, Hyrule, or in this case, the Great Sea, wasn't supposed to be Japan at all.), yet they had him wearing the yukata, anyways. Heck, he even wielded those Samurai-blades (I don't really know what they're called.).
Also, in regards to the scene where Misty is holding up a cross, there's actually a simple explaination for that (as well as the possibility of her being christian.)
I mean, yes, it's far more likely that it was for Vampire references, however hear me out on this one.
when Vampires were believed to exist, people often carry the Crucifix (in other words, the cross) because, since Vampires were creatures of Hell, and part of Satan's army, as well.
This was especially prevalent. in Bram Stroker's Dracula (the book, not the movie), since the plot had the main character being agnostic (I heard "Protestant", but it seemed more like atheism to me.), and said main character being disgusted at several people (supposed to be catholics) giving the character crucifixes. However, it's eventually realized by the main character what these objects mean, and then, in the end, seals up his daughters in the crucifix.
now with that history lesson aside, you can fully realize the significance of Crosses in regards to fighting Vampires.