All the flight that arrived so far were from Middle East, Singapore and some European countries.Japan would be one. I can go to Thailand and get into the Phuket sandbox, but even once I’m fully vaccinated Japan doesn’t have any system in place to let you skip quarantine.
There is a list for which country national is allowed in.
As for the quarantine required back home it is the tourist's personal decision. No one had asked them to go in the first place.