Music Without the Performer

Exploration Stage: Riverside Abode
From: Isabelle
Description: I examined the Riverside Abode to understand where the music is coming from. It seems to fill space and time. Help me study the biwa. I presume that the musician asked the Unseen Judges for a magical instrument that can play a melody on its own.
Completed: Hmm, how strange... The biwa looks completely ordinary, and my traps don't react to it. If you hit the strings, the melody will be out of tune, unlike the one that has fascinated the citizens and caused the snow.