If you live in Japan long enough, someone from home will announce they are coming. They have booked the flight. They are so excited. And when you ask where they are staying, there is a pause.
You send hotel links. You remind them. You remind them again. You send the arrival form link and explain what it does. Then they land, and your phone lights up: "Why does everyone keep asking me for a QR code?"
I have been on both sides of this, and here is my honest take. The unprepared visitor is not a bad person. But the way most of us host them quietly makes the problem worse.

To a lot of first-time visitors, the flight feels like the whole trip. The hard part is done, right? Everything after that is just showing up and soaking it in.
From where you sit, it looks very different. You know Japan runs on small details: where to stay, how to get from the airport, which forms to fill in before landing, how you pay for the train. None of it is difficult. All of it is easier before the trip than during it.
The gap is not laziness, usually. It is that they assume you are the plan. You live there. You speak some Japanese. Why would they research anything when you are a message away?
That assumption is flattering for about a day.
Here is the trap. You care, so you send helpful links. Lots of them. A hotel list, an article about IC cards, the government's arrival form, a note about trash cans being rare.
Your visitor reads none of it closely, because a pile of links feels like homework, and homework can wait. Meanwhile, every reminder teaches them that you will keep reminding. The responsibility slides a little further onto your side of the table each time.
So the QR code moment at the airport is not really a surprise. It is the natural ending of a system where one person prepares and the other person waits.
More reminders just means more ownership for you.

What worked better for me was one message, sent once, a few weeks out. Not ten links. One short brief with only the things that cause real trouble if skipped:
That last point matters most. Then stop. If they skip the brief, they will learn faster from a long airport queue than from your fourth reminder.
You are a host, not a travel agent. Saying that kindly, early, saves the friendship later.

There is a quieter cost to the unprepared visitor, and it lands on them, not you. When you are their only connection to the country, their whole trip shrinks to what you have time and energy for.
They see your neighborhood, your favorite ramen shop, your opinions. On your work days, they wander alone, a little lost and a little bored, waiting for you to get home. Then they fly back saying it was "nice," and you both feel vaguely let down.
Compare that with the visitor who arrives already knowing one or two people in the city. A local who offered to show them a market. Someone their age who wanted to practice English over coffee. That visitor has stories you were not part of, and that is exactly the point.
Your guest needs people besides you.
This is the part of the brief I would add now: encourage your visitor to meet a few people before they even land.
SewaYou is a map-based friendship app for meeting people nearby and anywhere in the world. Your visitor can browse the city they are heading to from home, start chatting with locals and other foreigners there, and line up a coffee or a walk for when they arrive. And the friendship does not have to end at the airport. Plenty of people use it to make online friends in another country with no travel plans at all.
It helps you too. While your guest is out with someone new, you get an evening back. Use it to see your own friends, or open the map yourself and meet someone nearby who knows exactly what a family visit week feels like.

Unprepared visitors will keep coming. You cannot make someone research a country they are excited about in a vague, abstract way. But you can change your part: one clear brief, honest limits on your time, and a nudge toward people who are not you.
They might still ask about the QR code. At least this time, it is in the brief.
Download SewaYou to meet people nearby or anywhere in the world, and help your next visitor arrive with a few friends already waiting.