kasa-koso
The gentle, almost secretive sound of dry leaves or a small creature moving through undergrowth. Softer than 'gasakasa'.
💡Hearing a lizard in dry leaves — 'Something went kasa-koso in the fallen leaves.'
落ち葉の中からかさこそと音がした。
There was a kasa-koso rustling from the fallen leaves.
I heard a ___ sound in the leaves — probably a mouse.
葉っぱの中から○○と音がした。ネズミかな。