Serenade to Kaysa is a side quest in Zelda: Tears of the Kingdom. It involves waking up Kaysa, one of the four Great Fairies who can be awoken in any order, but it has some prerequisites.
First, you’ll need to start the Potential Princess Sightings side quest chain at the Lucky Clover Gazette near Rito Village. Then, you’ll have needed to complete the Serenade to a Great Fairy at Woodland Stable.
If you’ve done that, follow the steps below to complete Serenade to Kaysa. Awakening The Great Fairy Kaysa was one of the easier ones to find, in my experience, so I’d recommend doing it before the others.
How to complete Serenade to Kaysa in Zelda: Tears of the Kingdom
To start the quest, speak to Mastro at the Outskirt Stable in Hyrule Field. The coordinates are 1447, 1266, 0032.
Mastro will tell you his troupe’s flutist, Pyper, is missing, and ask you to retrieve him. Mastro says Pyper followed his sister, Haite, to Highland Stable in Faron. To get there, follow the trail south of Lake Hylia. You’ll find him standing on top of a tree near the stable.
You’ll have to help Pyper before he’s willing to return. He’ll ask you to complete another side quest called The Flute Player’s Plan, which involves collecting 10 Sunset Fireflies. The best place to find them, in my experience, is in Pagos Woods Finra Woods at night, especially in areas near water.
Once you’ve gotten them, bring them to Pyper. He’ll ask you to fetch Haite, who can be found in the stable at night. Do that, and he’ll return to the troupe.
After you’ve done that, return to Mastro. He’ll ask you to find a way to transport his troupe to Kaysa. There will be a large zonai device with wheels attached to a slab leaning against a rock right next to him. Use Ultrahand to turn them into a cart by adding the loose wheel, the control stick, and the nearby cart.
Speak to him again and he and the troupe will hop on board.
Drive them up the rocky path starting at -1482, -1206, -0037 and follow it all the way up and to the right to reach Great Fairy Kaysa’s location. The troupe will then wake her from her slumber, and the side quest will be done.