Check-in without a counter is a bit difficult for foreigners. The first hurdle is the main gate number; it doesn't match the reservation number, preventing entry. Luckily, I had purchased Skype credits beforehand, allowing me to call local Japanese customer service and finally gain entry.
The second hurdle is entering check-in information on the screen, which again proved inconvenient. Apparently, in addition to the already paid amount by card, a foreigner's accommodation tax of approximately 1000 yen must be paid on the spot before check-in.
Next, I had to enter the information of each guest (passport scan), and then use the counter's video customer service screen to obtain the room number and password before successful check-in (those who don't understand Japanese must communicate entirely in English).
Finally, a reminder: remember the main gate number, otherwise you won't be able to get back in.
Then, be prepared for the fact that local Japanese also stay in these accommodations; their check-in is quick and convenient, but foreigners will face difficulties.
Original TextTranslation provided by Google