Upon stepping onto Hachijojima Island, Mami Sugiyama is captivated by the crystal-clear ocean, but suddenly feels flustered when someone calls out to her. The voice belongs to a man who immediately tempts her into intense sex on the beach. As she walks along the shore, a surfer unexpectedly appears—and to her surprise, it's her ex-boyfriend, whom she hasn't seen in a year. That night, accompanied by the sound of crashing waves, their rekindled passion ignites into fiery lovemaking. Now, on this southern island, they embark on a thrilling journey of fleeting, once-in-a-lifetime sex.