Summer Pockets is an adventure game set on Torishirojima, an isolated island in the Seto Inland Sea with a population of about 2,000 people. The protagonist, Hairi Takahara, a young man from an urban background, visits the island after his grandmother's passing to handle her estate sale. The narrative revolves around Hairi's interactions with four girls on the island.

The main characters include Shiroha Naruse, who has lost memories of her summer vacation; Ao Sorakado, who delves into the island's legends; Kamome Kushima, a high-class girl in search of a pirate ship, and Tsumugi Wenders, a young girl on a journey of self-discovery.