Originally Posted by
ConfusedInJapan
Thanks for your replies!
I booked the ticket myself directly on ua.com and used my Japanese credit card to pay for it. The home address recorded in their system should be my address in Japan (I have no other home address).
I don't have a US passport, and I travelled without visa (using visa waiver permit).
Perhaps I entered something incorrectly during the booking stage but I don't recall.
You entered the US illegally.
You cannot use the VWP for business trips!
Get a business visa.
I am astonished that you are not aware of this.
If you tell the CBP officer you are on business you will be deported and the airline will be fined which they will attempt to recover from you.