Torishirojima is a quaint, peaceful island located far from the city's noise, where time seems to move slowly. Hairi Takahara, a young boy with a wounded heart, uses his grandmother's recent death as a quiet excuse to leave the city for a summer retreat to Torishirojima. Upon arriving on the island, Hairi finds himself in a refreshing, laid-back atmosphere, quite different from the hustle and bustle he is accustomed to. After moving in with his aunt, Kyouko Misaki, he prepares to spend the summer helping her sort through a shed full of artifacts his grandmother collected over the years, alongside his cousin, Umi Katou, who is also staying with them. While adjusting to the island's slower pace, Hairi decides to spend his free time exploring. He soon meets the cheerful Tsumugi Wenders; the antisocial Shiroha Naruse; the wandering Kamome Kushima; and the sharp-tongued Ao Sorakado. Drawn into their lives and the island's subtle mysteries, Hairi is gradually swept up in a summer filled with fun, nostalgia, and life-changing moments that will stay with him forever.