When officials suspect that a person is entering Japan for non-tourist reason, that can be a reason re-entry to Japan can be denied under visa waver program. I knew a friend’s friend (US passport, US citizen) who went to Japan teaching English and was getting paid under the table, entered Japan under visa waiver for tourists. Before end of 90 days bought cheap ticket to South Korea and attempted to enter Japan again. Young person in mid 20s have just spent 90 days in Japan and attempt to enter Japan again. I guess it did not take a rocket scientist to start wonder how this person is affording to stay in Japan for this long…

Also, I heard that have to be little careful about mentioning volunteer work to immigration officials. Cannot work and get paid in Japan under visa waiver program. The volunteer work may not have monetary pay, but if a volunteer get free lodging and free meals in exchange for work from an organization in Japan then that can be considered as being paid in Japan.

Your friend’s daughter have to know what to say, what not to say to passport control officials at Japanese airport, and have proper documents.

I think proper thing to do for this young lady is to ask Japanese consulate visa section for information, rather than her parent’s friend asking opinions on travel websites.