Where is the next sage that will power up your master sword in wind waker?

If you've already beaten the wind temple, then the next sage is Medli (the bird girl.) She is on a cliff on dragon roost island. Gain access to it by going in the island and walking out onto an overhang on the second floor and use your grappling hook to get on the cliff. If you've already beaten the earth temple, the next sage is Makar (the leaf dude that plays the violin) Gan access to him by using your deku leaf to glide into the waterfall with music notes coming out of it on Forest Haven.