Pretty much the same as fast track anywhere that has it for general passengers, Business / First class passengers of course. In the case of T1 NRT, Star Gold in economy can also use it (assuming *A flight), but don't think there's the same benefit for OneWorld status members in T2. Though I've never seen more than a few people in line at NRT anyway except right around major Japanese holiday periods (New Years, Golden Week, Obon, Silver Week are the main ones)