If you mean the peculiar phenomenon where some J-Pop feels
more neurologically exhausting than music explicitly designed to sound violent, then yes—there is a plausible audio-production explanation. It is probably not a covert resilience program.
A lot of modern J-Pop is extremely
information-dense. You can get, simultaneously, fast vocal melodies, frequent chord changes, countermelodies, busy drums, synth arpeggios, guitar fills, backing vocals, sound effects, and very little empty space. The arrangement may change substantially every few bars. Your auditory system therefore gets fewer opportunities to settle into a stable prediction.
Gabber, by comparison, can be brutally loud and fast, but often has comparatively simple perceptual organization:
kick kick kick kick, repeating bass/harmonic material, recurring loops. Once your brain has inferred the pattern, much of the apparent extremity becomes predictable.
Death metal has a similar paradox. It may contain blast beats, distortion, growls, rapid guitar work, and complex rhythms, but its sound frequently forms relatively coherent perceptual "blocks": distorted guitars occupy one broad texture, drums another, vocals another. Dense, certainly, but often stylistically consistent over a section.
J-Pop can instead attack you with
continuous novelty:
- very bright mastering and prominent upper mids;
- aggressive compression/limiting, reducing quiet moments;
- densely layered instrumentation;
- vocals kept highly intelligible and forward despite the dense backing;
- rapid harmonic rhythm and unusually colorful chord progressions;
- frequent transitions, fills, modulations, and arrangement changes;
- multiple simultaneous melodic lines competing for attention.
The important distinction is therefore
acoustic intensity versus cognitive load. Gabber may punch your cochlea harder. Death metal may sound more threatening. Hyper-dense J-Pop can make your auditory cortex fill out paperwork at 180 BPM.
So, as for what Japan is hardening the population for: based purely on the sonic evidence, apparently
processing seventeen independent streams of information while somebody modulates to a new key and a cheerful anime character explains the power of friendship.