Igarashi hits rock bottom as he loses his family and his job. He flees society on a ferry to Hinoshima - “Japan’s last hidden paradise.” There, he meets Tonbo, the island's only middleschooler. As Igarashi explores the remote island, he senses something odd—a pervasive golf theme, despite no golf course or known golfers on the island. What secrets does this golf-enveloped, mysterious island hold?

Tonbo impresses seasoned golfer Igarashi with her unique style, playing solely with a 3-iron. Intrigued, Igarashi adapts his wedge with her 3-iron's grip and coaches her on its use. Teaching Tonbo reminds him of instructing his son, Rintaro, evoking regrets about robbing Rintaro of golf's joy.

Igarashi's unease with Tonbo's golf stems from the fact that she doesn’t feel the pressure that comes with a competition. On the island's cliff-top course, he sees his past failures with his son in her. Yet, Tonbo's actions make him reconsider, accepting her as she is. Learning from Yoko that Tonbo hates the idea of leaving, Igarashi realizes that a change in perspective, not location, is needed.

Despite meeting for the first time, Tonbo and Tsubura hit it off and decided to play a round on the island's golf course. Tsubura is amazed by Tonbo's free-spirited style. However, Tsubura's own approach is methodical and precise, with calculated shots. Inspired by each other's contrasting styles, a competitive spirit grows within Tonbo, determined not to lose. How will their match turn out?

Igarashi travels to Akureki to meet Mr. Kuta, the designer of the Hinonoshima golf course. He shares his past with Tonbo, who fears leaving the island. The next morning, Tonbo joins him willingly. Mr. Kuta warmly welcomes them and shows them a special one-hole course he created in the forest by a small pond.

Mr. Kuta asserts, "Tonbo's golf style won't work in competition," and takes Tonbo and Igarashi to a challenging practice green. As Tonbo tackles the monstrous green all day, she starts to appreciate the kindness of Igarashi and Mr. Kuta.

Tonbo decided to leave the island, which greatly impacted the residents of the surrounding islands. Amidst the mixed emotions, a farewell golf tournament was held, with just one day left until departure.

Tonbo and Hinoki hit the golf course for practice. As Tonbo unleashes bold, carefree shots, Hinoki’s view of her begins to change. Despite the strong winds, they exchange impressive plays. Meanwhile, Igarashi arrives with a special gift for Tonbo, who's just started her new life in Kumamoto.

Though on the first day of the Kyushu Women’s Championship there were many players around Tonbo's age, she ended up paired with a housewife golfer named “Shima-san.” Her skills being just barely above the cutoff line irritates some fellow competitors. However, as the championship progresses, Shima-san’s unique approach to golf begins to influence her fellow competitors playing style!