Playtime With Cottla
In Kakariko Village, during the daytime, you can see a child running around with a red [!] above her head. Speak with her and you will learn that she is bored because her older sister is too busy now that their parents are currently out.
She will give you two options to pick from for a game. You can pick either to start the sidequest. We opted to pick hide and seek. Cottla will go hide, and you have until the evening to find her, after which time she has to go home for dinner. Cottla is hiding around the back of Impa’s wraparound porch. Go to Impa’s house and run around the porch until you see her crouching in the corner.
Your reward for giving her a good time is a Rock Salt.
If you chose to play tag instead, then you simply have to keep up with her as she runs.