Instructions
Press the "A" button while standing next to the watering pond on the side of your horse stable. The first sprite will appear.
Fill your watering can at the pond 10 times by pressing the "Y" button to find the second sprite.
Upgrade all your tools to the mistrille level by talking to Blacksmith Saibara in town. He requires a certain ore for each tool upgrade; each is found by mining rock with your hammer around the game world, and especially in the mine. The cost of each tool upgrade increases by 1,000 or more gold. When the watering can is upgraded, the third sprite is yours.
Use the upgraded tools to clear and water a new area of the game each day. Keep track of what squares have already been watered so as not to repeat the search. Eventually, the three hidden sprites will appear.
Water many crops of land to get the last few sprites. A new sprite appears when the total number of squares watered in the game reaches 1,000, 5,000, 10,000, 30,000 and 50,000 squares.