In modern-day Japan, 13-year-old Hajime Yasaka moves to the countryside to stay with his grandfather. On the way to his new home, a lost Hajime finds himself in a cafe called Ark, where he immediately falls in love with one of the waitresses: the gorgeous Sayoko "Arashi" Arashiyama. While Arashi is initially unconcerned with the boy, her attitude quickly changes after she grasps Hajime's hand, leading her to believe they are "connected."

As it turns out, Arashi is anything but a regular teenager—in reality, she is the ghost of a girl who perished in World War II. By touching a man she connects with, she gains the ability to travel back in time. Delighted to have found someone who can unlock her powers, Arashi asks Hajime to help with her mission: to save civilians from the carnage of the war that claimed her life. Smitten with Arashi, Hajime readily agrees. But as the two get further involved with Arashi's past, they soon discover that she is not the only one able to transcend time.