Thank you for your message. I willingly answer for your question.
You can stay abroad for 33 days, so I think you can connect with many people who is same age with you during the program. Don't have to worry about it too much. We, especially Japanese, tend to be shy in front of the strangers, but I think having a posture to be positive is really required. Don't care about making mistakes. Of course I know you don't make mistakes.lol The important thing is to have some fun:)
As for me, the people in the US are mostly warm and nice. In addition to that, the family who apply to the international program such as homestay are eager to have a chance to communicate with foreigners, so they also will be kind to you, in fact. Even if you cannot tell your feeling properly, the enthusiasm will help you at last, I believe.
In the first few days since you arrive at the US, you will notice that the speed of English is much faster than that of IE class. However, around the 2 weeks, you will get used to catching its speed. So, the important turning point is around 2 weeks! Until then, I recommend you to continue good works as much as possible.
I'm wondering that these advice will be actual acvice for you, but I think you can do well. If you have something to ask me, feel free to do so;)