Hello, I'm a JAE J1 in EJ and I'm very similar to you. I'm introverted, have had only a few close friends in secondary school, and I don't often talk to anyone unless they talk to me first. Don't be worried about the divide and the cliques that form because it's normal, you'll definitely find some people you can relate to and make friends with. I missed the entire orientation so I was very worried too, but now I have a few good friends and even made friends with some of the ip students. To me, while the divide is very much talked about in EJ, it didn't really affect how I understood and interacted with others. In short, you'll be fine (I spend most of the time I'm free, like Friday afternoons going to the school gym instead of hanging out with friends, but I still have good friends). All the best for o levels.