This mysterious maiden lives behind the waterfall south of your farm. She maintains the water shrine in a secret world that most people can't get to. Emiko is a timid person, and since her duities with the shrine is a solitary task, she enjoys your visits.
The path to Emiko's water shrine can not be unlocked until you've reached your second year in the game. Leave your farm area on a non-rainy day between 9:00 pm and 2:00 am and you'll discover something unusual with the waterfall by Lloyd's house. As you investigate the waterfall, you will observe a path leading through it. As you go down the path, you'll meet Emiko for the first time.