I've made a very incomplete map of Japan's sirens here if you want to check it out: https://www.google.com/maps/d/edit?mid=1n1oevyKeZFbwCtjn-jEMpuwRFqSAow6y&usp=sharing I have a few Japanese siren locations you may add. Camp Fuji 35.31977, 138.87442 - Cooper WAVES HPSA-?104 35.32168, 138.86785 ...
LA had a siren system, like the other cities around it. It comprised of Thunderbolts, SD-10s, Mobil Directos (Culver City only IIRC), 500s, a few Chryslers, Model 5s and 1 2T22.