Chords, scales, and keys are all Western concepts. You might want to study some non-Western music traditions, in many of which harmony plays little role. Or even Western ones not based on quintal harmony, like a lot of jazz, not to mention all the experimentation in atonality in 20th century Western art music.

All languages ultimately relate to the way humans produce sound. That does not mean that English linguistics is tremendously useful in analyzing Japanese, even if it's better than nothing.