Back when I was a Yamaha dealer (although I left retail in '88) they put D'Addario strings on all the instruments when they came into California. That's according to the Yamaha dealer newsletter we used to get, and matches my experience with D'Addario on guitars and basses.
Of course that's been so long ago they could have been through every string maker in the world now, and might even own their own string winding equipment in Japan. At one time Yamah's goal was to be able to provide everything a musician needed for a gig, including the vehicle to haul it, except they never sold any cars in the US.
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"Without space, music is just noise piling up on itself." TRK
"Don't play your instrument, play music." Feral Feline
Lakland Owners' Club #248