bit late, but i found a map (not yours) that contains even more of them, it can be found here :
https://www.google.com/maps/d/viewer?mi ... 567588&z=5
i cannot belive how many there are on that map, but apart from that i can also tell you that a japanese channel made a up-close video of the siren on the iga city hall, and its here : https://www.youtube.com/watch?v=csTZcYn_DPQ (and at 4:42 the siren activates)