gasa-tto
A sudden, startling rustle in bushes or undergrowth. Something moving in the vegetation.
💡Hearing something in the woods at night — 'The bushes went gasa-tto and I froze.'
茂みからがさっと音がした。
There was a gasa-tto rustling from the bushes.
I heard a ___ sound in the bushes and jumped back.
茂みから○○と音がして飛びのいた。