This is 100% the fault of some combination of the Chinese Foreign Ministry and IATA (TIMATIC). The entire purpose of TIMATIC is to provide a quick & correct means for agents who are trained solely to operate the database and not as international lawyers, to determine whether an individual has the proper documents.

There is no reason for a DL agent to know that China considers a ticket to originate at NRT when the ticket in fact originates in the USA. Unless TIMATIC specifies that ticket origination is to be considered the immediately preceding station. As the language for TIMATIC is provided by respective government authorities, put into form and then reviewed for accuracy by government officials before it is posted, it falls on either China to have caught the missing language or IATA for not having included what China provided.

Snarky comments about China fining DL are way off base as are the comments about DL agents not knowing Chinese rules. They do, it's what China provided IATA and they see in front of them.

I would hope that DL makes this right for OP as a customer service gesture and also raises it to IATA as the language is incorrect.