I contacted AA in a post on X, and they replied to me. They said the tickets themselves are fully refundable, but there is a JPY ¥30,000 penalty per person that applies when requesting the refund. At the time of purchase, the website said that the tickets are fully refundable, but didn't mention anything about a penalty, so be sure to double-check refund conditions before going through with the purchase. (This fact is not stated in the conditions of carriage nor in the Refunds FAQ.)