>>2356377>synthesizersThis, and even more.
Yamaha manufactures some synths, but also everything from prized grand pianos like the CFX to reliable entry-level instruments: guitars, violins, flutes, clarinets, saxophones, drum kits, electronic drum pads, absolutely everything. They even manufacture motorcycles. Yamaha stuff is everywhere around the world, just like Kawasaki motorcycles.
Most arranger keyboards used to play Arabic music are Korg keyboards, and they manufacture other ones used all around the world for other styles. The Korg MS-20 was one of the most popular analog synths in the 1980s because it was cheap and was well designed, and it's still popular to this day.
80% of the effect pedals used by guitarists are manufactured by Roland under the name BOSS, because they are cheap and their construction is solid as fuck. They also manufacture synthesizers.
Then you have Ibanez for metal guitars, and some other brands I forgot.
People needs to realize Japan was the China of the 1980s. Back then, Americans hated Japan just as much as they hate the Chinese now. It changed after the real estate crisis and the Plaza Accord, but Japan still has some serious engineering and manufacturing skills. It's not a "globally irrelevant country", far from it.