I was more or less prepared for the no photos thing (if indeed it was a thing, which I still don't know), since that was the standard in the U.S. prior to widespread cellphone use. You couldn't bring any kind of recording device into a concert venue unless you were officially there with the press. But then everyone had smartphones with good-quality cameras in them, and venues gave up on the photo/recording ban.
But there are a lot of ways in which Japan still operates in archaic ways despite current technology (like, for example, my having to go to Tower Records to buy albums on CD). And there could well be a cultural understanding that you just simply don't try to take pictures of a concert because why would you do that it's rude.
That bit, though, where there was total silence after the first song and all applause was held until the end of the set? I was completely unprepared for that. I know there are traditions in classical music circles where you only applaud at specific intervals, but I've never seen that at a metal show until this one.
Also, the actual translation of "encore" in Japanese is アンコール (ankouru), where the final "ru" would only be partially voiced. But the crowd was definitely saying a fully-voiced "re" at the end of the word, giving each syllable equal weight as basically a three-beat chant.