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?

While visiting a golf course on the island made by the residents, Igarashi witnesses Tonbo's incredible super shot. Intrigued by each other's golf skills, they decide to play together again the next day. While playing, Tonbo opens up about her love for the island. Returning at sunset, Gon encourages Igarashi to experience the island's starry sky, under which Tonbo reveals her past.

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.

As Igarashi adjusts to island life, he observes the interactions between Bunpei and Yoko. Golfing daily with Tonbo, he sees how the island has influenced her impressive shots. Inspired by her uninhibited style, Igarashi wants her to try tournament golf. However, he feels there's something unusual about her play. Unexpectedly, a squall hits them on the course.

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.