Once they do arrive at their inn they check-in and feel safe. If someone knocks on the door, they open it. Money wise, Japanese know how much money to bring with them when traveling around Japan. Prices are clearly marked. Merchants expect to be paid in cash.
Credit cards are rare but growing.
If they need more cash they can quickly find a public automatic teller machine. No particular precautions are necessary. When Japanese people travel abroad, however, many of these habits make them vulnerable. In airports and bus stations it is important to keep close watch on your luggage. Coin lockers and toilets are hard to find.