For me, it’s actually the bar scene (I’m early 30s) in America.
Don’t get me wrong, I love living in Tokyo, which is why I moved here, but I really miss the way Americans and Europeans talk in bars. It’s not always the case of course, but I’ve had so many amazing conversations with random people in America and while traveling Europe that I just don’t get in Japan.
If you meet a random Japanese perosn at a bar, they’ll usually use you to practice English so the conversation will be pretty basic, and if they’re somehow able to communicate at a sophisticated level, the cultural differences will prevent them from fully engaging with you.
I also miss great italian food, like italian food made by some big fat guy in NYC. I feel like the italian food in Japan is always a little bit too sweet.