After a busy school year, Izumi and his girlfriend Sophia finally start their summer vacation. Izumi receives an invitation from his father, Kuroda, to spend the summer at his house in the countryside by the sea. Not too keen on the idea, Izumi suggests that Sophie come along, since he doesn't want to be alone with his father.
But as the days go by, Sophia and Kuroda begin to grow closer, and their relationship begins to change beyond the typical father-in-law/daughter-in-law dynamic. While Izumi enjoys his carefree vacation, he has no idea that something is developing between Sophia and Kuroda right under his nose.