Koharu and Hiyori, who became "sisters" due to their parents' remarriage. The long-awaited school trip to Okinawa has finally arrived! During their free time, Hiyori and her friends challenge themselves to "tuna fishing"! Will the somewhat awkward relationship between the sisters be restored through tuna fishing...? This is the 9th volume of the cute, fun, and delicious new era of fishing outdoor comic, which has also been adapted into a TV anime!