Makar

From Zelda - Wiki on Neoseeker

Makar is a young, mischeivous Korok who lives in the Forest Haven. One day, when flying above the Forbidden Woods, he falls and ends up trapped inside. On top of that, and he is the lead cello player in the Korok ensemble, and they cannot complete their annual seed spreading ritual without him. It is up to Link to rescue him and let the festival begin, so that new trees may grow all around the Great Sea

It is later revealed that Makar is the new Wind Sage, and he, along with Medli, helps return power to the Master Sword. You can find him playing his cello behind the waterfall just outside of Forest Haven.