Genzō Senō, grandfather to Junpei and Kanta, lives and works as a fisherman alongside them on Shikotan Island, his existence deeply intertwined with the surrounding sea. After the Soviet occupation post-World War II forces the family from their home into the stables, the Japanese residents are ordered to evacuate on September 25, 1947. Genzō resolves to stay on Shikotan, choosing to live his final days in the environment that defined him. This decision leads to permanent separation from his family. Fifty-six years later, Junpei and Sawako return to Shikotan, paying respects at Genzō's grave and affirming his enduring bond with the island and its seas.