My most general advice would be for them to go to (start) uni there where you are, take a couple years of Japanese (along with other courses), and then do a year abroad here in Japan. Or, if they need to get here faster, do a year of Japanese, and then a summer, or one term, abroad.
This will skip all uni exams, applications, and so on. It also provides a goal--get into and then study here in our home country for a year or two, and the reward will be a year abroad. Tho some do, most year abroad programs don't have any testing/vetting (having the money for it is a more common hurdle).
There are a few uni here that accept students from abroad. Ritsumeikan, ICU, Sophia (Jochi), and some others. Use google to get some info on those.