Thank you for all your help
About a month ago, I posted a question to ask that whether there is a firearms training course available to foreign nationals, in my case, a citizen of Japan.
I am glad that a lot of people kindly answered my questions, even though it must have been fairly rare, and my English is not so awesome.
Thank you for all the answers.
I recently found FrontSight does accept students from other countries.
There might be some other schools that are open to foreign nationals, but as far as I have searched, there are not many of them.
I also found that there are some shooting ranges in Guam which are open to tourists.
Although they are primarily for tourists, at least I wouldn't have to worry about leagal issues, so this might be a best compromise.
Also, some of them seem to have a wide variety of guns.
I am not sure whether they have courses in which I can learn the basic of the shooting, and I am still very much interested in taking courses which are held on US Mainland.
In the meantime, as I continued with my searching, my job started getting busy again, and right now I am not sure when I can take a week-long off next time.
I'm hoping to take some vacation during summer or autumn, but not sure.
So the whole plan has come to kind of a pended state,
but I have gained tons of useful information that I can use in the future, and I still definitely give one a try,
so thanks for all your help and see you again!