Twenty-six-year-old Hiroto Suwa; his wife, Naho; and their old high school classmates—Takako Chino, Azusa Murasaka, and Saku Hagita—visit Mt. Koubou to view the cherry blossoms together. While watching the setting sun, they reminisce about Kakeru Naruse, their friend who died 10 years ago. Mourning for him, they decide to visit Kakeru's old home, where they learn the secret of his death from his grandmother.