Prior to shorthaul taking over the NRT flight, there were 2 Longhaul Japanese speakers on every flight. At 1 stage it was only 1, but after about 2 years, with enough complaints it was raised to 2 - this was not made a requirement per say, but in the bidding, 2 were planned. In short hauls attempt to undercut mainline, these language speakers were removed.
That is until the NRT groundstaff were inundated with complaints from Japanese passenegers, not just about lack of language speakers but also because of service (this presumably was teething trouble) - the longhaul cabin crew, had been giving special training for Japanese pax - being made aware of cultural issues, and service issues - the money saving solution, was to put an extra crew member on board - purely as a language speaker - they are only meant to help out over PAs or to deal with customers when there is a problem. They dont work carts, so they cant actually serve the passenegers.
Because of the pay structure, the PER-NRT flights have gone from the most popular flights, to the highest sick rates. In many cases it is young casuals who operate the flights.
Ultimately it is the passengers who suffer.