I've been introduced to the Nature Sprites, and met them all. In previous Harvest Moon games, they used to help you out with things, such as unlocking new areas in A New Beginning, or using them as slave labour in HM:DS (They'll do anything, if they like you. They also really liked flour. To an unhealthy degree).
What is their purpose in Story of Seasons? Can they help you with chores on your farm?