The Earth Sage
Nintendo Gallery Note: Get any figurines made that you still have pictographs of in your picto box, then save the game. You are about to encounter some characters that you only have one chance to get a pictograph of.
With three free picto slots, warp to Dragon Roost Island. Go up to where you played the mail sorting game and go through the door to the left that goes outside.
Get a Picture of the Disappearing Kogoli
Nintendo Gallery Note: The Rito at the far right is Kogoli. He will completely disappear from the game after you awaken the next sage, so you must take a picture now to get his figurine. He is difficult to get a pictograph of. Stand across from him, far away from him on the rail, then walk toward him on the rail so that you are just close enough that he turns his head toward you. Take the picture, getting as much of his body in the picture as possible. To be safe, take three pictures of him, then go to the Forest Haven and get his figurine made right away so you can have three free picto slots for the upcoming one-chance-only characters.
From the platform with Kogoli on it, turn right and grapple up to the ledge, and climb up. There, you will find Medli playing a harp. Walk up to her and she will talk to you. Don't play the Earth God's Lyric yet.
Take Medli's Picture
Nintendo Gallery Note: Save and take Medli's pictograph now. You won't be able to get her picture after the next dungeon. Once she has talked to you, she will turn to face you. Back up and take the picture. You can take her picture during the next dungeon, but you might as well do it now. You can go get her figurine made now if you wish, or just save the game and don't save again until you have had her figurine made.
Play the Earth God's Lyric for Medli
After Medli has talked to you, go up to her and play the Earth God's Lyric. After a cut scene, she joins you in your boat. Warp to Outset Island, sail east to Headstone Island, and you will automatically land.
Go up to the slab with Medli near you and play the Earth God's Lyric.