When timid eleventh-grader and math genius Kenji Koiso (Ryunosuke Kamiki) is asked by older student and secret crush Natsuki (Nanami Sakuraba) to come with her to her family’s Nagano home for a summer job, he agrees without hesitation. Natsuki’s family, the Jinnouchi clan, dates back to the Muromachi era (1336 to 1573), and...