Kannonyama rice fields - Kodama?

I was recording another river just outside the mountain village of Seki when I suddenly heard the most curious sound coming from a satoyama just behind me. This mountain in particular was absolutely marvellous to listen to and walk through and had an ancient and mystical splendour about it, so I had already developed a kind of reverence for it. As a result, when I first heard this sound that I couldn’t identify I assumed it was some sort of mountain spirit. Turns out it was dozens – if not hundreds – of tiny invisible frogs that would sing out in unison, but would fade out at any sign of movement amidst the mountains and fade back in once the apparent threat had passed (in this recording you can hear this affect caused by a passing train in the distance as well as when I stood up to stretch my legs).