Climb the stairs to the right, then walk up the corridor until you reach the Mirror Chamber. Fight off all five Twilight Beasts as a wolf or not, then get close to the statue, use the Spinner and get off on the summit. Place the item in the centre, which will plunge the statue under the ground and make the Mirror of Twilight come out of the sand. Midna notices that the mirror is shattered. Some sages says that they have been guarding the mirror since long ago and that it has been fragmented by evil magic owned by Ganondorf. The three other fragments now lie hidden across Hyrule and you should go find them.
Go back to Hyrule Castle Town, speak with Telma in her Bar, then check the map on the table to find where Ashei is.
Note: If you have 20 Poe's Souls, go back to Jovani's (if you don't have all of them yet, you can come back later). To do so, go to the western street, in the small courtyard with cats, turn into a wolf, use your senses and dig near the wall. Talk to Jovani that will reward you with a bottle containing Great Fairy's Tears.
Afterwards, warp to Zora's Domain and turn back to your human form a little further. Speak with the Zoras, especially the one east of the pond and those close to the throne, then let the current bring you to the bottom of the waterfall. Swim east, climb on the bank, then speak to the Zoras and follow the passage. Talk to Ashei, who will tell you about a beast and give you Ashei's Sketch. Leave, swim north and talk to the Zora at the bottom of the waterfall, so he brings you back to the throne room. Show your sketch to the Zoras to learn more about the fish drawn on it. Then go to Kakariko Graveyard. Go to the back of it, get in the small tunnel and swim across. After meeting with Prince Ralis, show him Ashei's Sketch. He will tell you that this fish is a reekfish, that he can be found near the Mother-and-Child Rocks, and will give you his Coral Earring. If you want to, place a Water Bomb next to the underwater rock to the north to create a shortcut towards Lake Hylia.
Go back to Zora's Domain and go down to the bottom of the waterfall. Get on the west bank where two rocks emerge from the water. Check that red fishes are around you, then cast the line to get one of those reekfishes. The technique is the same as in Ordon village. Wait for the coloured "stick" to be vertical, then as soon as you see a fish getting close and the stick sinking in the water, raise your fishing rod (wiimote) and the fish should be hooked. Then keep your fishing rod raised for a few seconds to fish out the fish. As soon as the fish is on the bank, turn into a wolf and use your senses to smell its scent. You will learn the Reekfish scent! Go through the pond towards east and take back the path under the mountain.
Go ahead and follow the scent to the east while avoiding Wolfos. When the scent is going really upward, go a little bit to the right and climb on the ice blocks. Go on following the scent, then when the scent goes up a big rock, get around it from the right side and go back to the scent. At the following area where the scent goes up, run and rush in the snow to make some of it fall. Go on, go right and follow the scent. Get close to the Howling Stone, repeat the melody twice so a Wolf Mark appears, then keep on following the scent.
Dig where the scent goes underground, then go back to your human form and climb the ladder. Climb the stairs, climb the vines and open the door. Go back to your wolf form, go ahead and get rid of all three Twilight Beasts. Turn back to your human form and get close to the yeti. Tell him you are looking after something and he will tell you about a mirror piece he found. Now run and roll against the tree, then get on the fallen ice block. Glide towards the yeti's manor while avoiding enemies and obstacles. Then get in the manor that is none but the...