The new entry procedure for Japan:

Japan is Open for Visa-Free Tourism! Here's What You Need to Know Before Going - Travel Codex

Same for me when I flew BOS-DFW-NRT on AA in Sept. I did VerFly app with Green Active, and Blue screen on MySOS. I was able to do online check-in at AA.com and at BOS checked baggage and the agent did not ask me to see any documents. At DFW, spending short time at the Flagship lounge I headed to the gate for NRT flight. At the gate I was told I have to get a stamp on my boarding pass. I was not aware of this until I got to the gate. The lounge attendant and agent at BOS did not mention about this. Only one agent was doing this, checking documents and stamping boarding passes, obviously long line. There were two guys heading to Bangkok and were pissed off about the long line to get a stamp on a boarding pass at the gate. One guy said out loud to the agent at the podium; "We are elite and is this the only line?!" They were told to wait in the line, and one guy was saying "AA is going to hear about this!"

Now that the restrictions to enter Japan has lifted, I wonder if this is still going on with DFW-NRT flight on AA. There are still connecting passengers heading to the countries with the entry restrictions, so it is possible that this is still going on.

This was a typical occurrence even prior to COVID.

The first time I flew there (8 years ago) I recall getting to the gate from the lounge to hear my name being called out just before boarding was to begin...only slightly anxiety producing

IME (as detailed elsewhere) UA does not even do a minimal scan, as the GAs missed my expired passport and permitted me to board an international flight. Thankfully I was not deported on arrival due to the discretion of the Dutch immigration service. Of course, most are not so fortunate, particularly in Japan.

They absolutely can. It's in every major airline's conditions of carriage.
Very funny. But no. That doesn't happen. Ever.

Because the airport agent saw something that looked sufficiently like a visa to allow them to board.
The airlines don't pursue a lot of customers for the cost of removal because the legal and other costs of doing so will often exceed the amount claimed, especially when it isn't clear that the customer will be able to pay the judgment.
Back in paper ticket days, they'd probably just have lifted the coupon for the return journey and let the back office sort it out.

So interestingly, I was reviewing my copy of the IATA ticketing handbook (a PDF of the 39th ed from 2007 is readily available online with a simple google search) which has guidance for this exact situation. I actually thought of this thread, but wasn't going to bring it back up, but now that someone else has I'll add what the ticketing handbook states in
2.23.13 Inadmissible Passengers
-Delivering carrier is responsible for ticketing the inadmissible passenger to new location advised by authorities
-If passenger has a return ticket that should be used. If the return ticket isn't valid for the destination they're being sent to, any remaining coupon value on the ticket should be applied towards the new flights
-Endorsement/fare restriction requirements are waived
-If the passengers remaining ticket doesn't cover the new flight they're being put on, the delivering carrier should collect the fare difference
-If the passenger can't pay the fare difference, the delivering carrier still needs to ticket them for the outbound flight, however the cost is split among all carriers who participated in transporting the passenger to the point of inadmissibility.

The last point is important, because in that case where the passenger can't cover the fare difference, the airlines obligation is only to return them to the point dictated by authorities, not necessarily their origin. So if for example the itinerary was ORD-SEA on BB and SEA-TYO on CC. Passenger is refused in TYO and airline ordered to send them back to the states. If the passenger can't pay the fare difference, the only obligation of CC is to get them back to the states, not necessarily to ORD (and BB & CC would share the cost for the TYO-USA flight the passenger needs to be put on).

Also as others have discussed there is a distinction between inadmissible person and deportee. An inadmissible person is refused entry/ordered removed before ever being allowed in, therefore they're not a deportee. On the other hand, a deportee is someone who was legally admitted to a country and then later ordered to be removed. When it is an inadmissible person, it is that person/the airlines responsibility to cover the fare of the transportation. When it is a deportee, it is the country (subject to local laws/regulations) ordering the removal who needs to provide the ticket fare.

Exactly right. Thank you. Having spent over 20 years in a position involved in these immigration refusals at a major international airport, I agree 100% with all your points.

Sorry if you've never heard of it, Jim, but that is EXACTLY how it works. Airlines are not extracting more money from a customer - they're just using the ticket that was bought for a journey from A to B and back to A for that same journey. It doesn't matter that the flight from B to A isn't on the day originally wanted by the passenger. In all my experience (over 20 years as a manager at a major international airport), we never, ever tried to collect extra for breaking minimum stay requirements etc.,so we merely used whatever ticket was held. However, if they had arrived on a one-way ticket only, we would advise the passenger that the airline was entitled to follow up with a claim for the unpaid flight. We would subsequently complete the internal paperwork, though I seriously doubt that any further action was ever taken by our accounts people!
And as others have said, the responsibility for holding correct documentation always lies 100% with the passenger, not the airline. Any checks that the airline makes on departure are purely to protect themselves against fines or sanctions by the receiving country and not as an additional layer of protection for the passenger, even though refusal to accept a passenger for a flight might have that same outcome.

IATA rules are all well and good but are an agreement between carriers. The agreement between the carrier and the passenger is the carrier's conditions of carriage. And the conditions of carriage allow the carrier to sue the passenger for the excess fare in this instance.
I agree. The case under discussion in this thread was the former, however. Additionally, the carrier's liability may differ depending on whether the passenger was refused for invalid or insufficient documentation (higher liability) or something they said/did at passport control or their history (lower liability as carrier could not have known the passenger would be refused).

Unknowable? It was widely known a visa was required to enter Japan for the past 2.5 years.

Good riddance. I am sure your presence will be sorely missed.

The airline has an obligation to remove the pax from the country they cannot enter, as directed by that country's authorities. The airline must do this, regardless of whether anyone can pay them. The delivering carrier erred by permitting an inadmissible pax to board.

IATA has an agreement to split the cost of doing this among the delivering carrier(s) should it happen.

The operating carrier can, under its contract of carriage, pursue damages from the passenger for the costs it incurs. In practice, this last step almost never happens because (a) in the case of a round-trip ticket, the return coupon is normally used, and (b) I would imagine in most other cases, the pax can obviously not afford the additional cost, so it's not worth pursuing.

The issue is now moot as the visa waiver program has restarted. The thread is now "Japan sucks," vs. "Passenger sucks," and the OP has left the discussion - which is too bad because I was hoping that we might hear from the OP after a successful visit to Japan.
Time to close the thread?

Nothing in this thread has convinced me that the passenger had a visa. He had one of the main documents required to allow him to apply for a visa, but he did not have a visa.

No he had an ERFS document, which is in effect a visa invitation letter that you bring to the embassy or consulate to document the receiving/inviting organisation. These are quite common to apply for visas for many countries. I would imagine certain nationalities would even need them for entering the US. I have been issued more visa invitation letters than I can possibly remember.

The issue is that many of us EU and US passport holders have forgotten what it actually means when you are required to go through a full visa process. As we had the benefit prepandemic of very rarely having to do it. The ERFS process was not particularly badly described or cumbersome at the point where you could start entering as self organised tours.

The surprising point was that it was there for a country that we fortunate EU and US passport holders used to be able to just waltz into, and people got caught in not having done their preparations. And United got caught in not checking the documents properly.

No wonder ANA and JAL does a full document check for connecting passengers before letting them board the plane to Japan.

How about these words from the actual immigration clerk: “Your visa no good.” Didn’t say, “That piece of paper you presented that is not a visa no good.”