Flying from EWR-NRT round trip in January. Noticed on my itinerary that the outbound leg is in D class and the inbound leg is J class. Both on 777-200ER and cabin configuration appears the same.

The FAQs post states that the fares are as follows:

D – First, First with International Connection
J – Full Fare BusinessFirst

But my itinerary says the D fare is First/Business First. I assume that both are just used to refer to BusinessFirst, but is there anything I'm missing? What's the difference between the class of service bins on this particular flight (I have no connecting flights, either - just EWR-NRT).

Thanks!