I just checked out the Nanjing Airport wiki on your behalf, which claims there is an MU flight from NRT to NKG, but I couldn't find evidence of such when I searched on Kayak. Perhaps it exists, but only flies a few times per week. In any event, since aa.com won't sell it to you, I'm guessing that going this route is probably prohibitively expensive.

So, that leaves your friend with PEK (overnight required), PVG (possible overnight required), AA to HND and connect to JL to SHA and train from there (I'm not sure about the layover situation, but let's assume not very good due to restrictions on longhaul flights at HND), and several double connects (e.g. NRT-ICN-NKG, NRT-TPE-NKG).

Personally, I would just fly OZ, BR, or LH the whole way and be done with it, but I understand the desire to use those EVIPs.

As such, I believe that PEK is probably your friend's best bet, and maybe fly back from PVG. On a related note, I visited the PEK Hilton for the first time today, and was simply blown away... simultaneously one of the nicest Hiltons AND airport hotels that I've ever chanced upon (far better than the GH at ICN, just to provide a frame of reference).