Having recently moved to the countryside to live with his wealthy grandmother after a personal loss, Gen begins to notice odd details about his family's history in the quiet estate. An American student researching the Hiraga lineage arrives, expressing strong interest in his unusual trait and its alleged ties to lasting vitality. Gen partners with her to examine old records and hidden patterns behind the early deaths that claimed so many relatives. As the clues mount, he races to uncover the truth before his own time runs short.