Tonbo Ooi, the protagonist, lost both of her parents in a car accident when she was young and was raised by her grandfather, Gonji Ooi, a fisherman on the island of Kagoshima in the Tokara Islands. Tonbo learns to play golf while using her father's inherited No. 3 iron on the island's three golf courses, which were built by the islanders themselves.

The story begins with Igarashi, a man who can no longer work as a professional golfer, visits the unexplored Tokara Islands in Japan in search of a job. Igarashi had given up on playing golf anymore, but his encounter with Tonbo, greatly changed his fate.