The Japanese Box Office sensationWhen timid eleventh-grader and math genius Kenji Koiso is asked by older student and secret crush Natsuki 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 and they’ve all come together to celebrate the 90th birthday of the spunky matriarch of the family Sakae. That’s when Kenji discovers his summer job is to pretend to be Natsuki’s fiancĂ© and dance with her at the birthday celebration. As Kenji attempts to keep up with Natsuki’s act around her family he receives a strange math problem on his cell phone which being a math genius he can’t resist solving. As it turns out the solution to the mysterious equation causes a hijacking of the social networking site through which most of the world’s social and business traffic flows. It’s up to Kenji and his new fake family to put reality back in order.