In the wake of their parents’ divorce, 12-year-old Koichi (Koki Maeda) and his young brother Ryunosuke (Ohshirô Maeda, Koki’s real life brother) have been split up aganist their will. Koichi lives with his mother and grandparents in Kagoshima, in the shadow of a constantly rumbling volcano. Ryunosuke lives a comparatively spirited life with his rock-musician father in Fukuoka. When Koichi discovers that a new bullet train line is due to open connecting the two towns, he determines that the intense energy generated by two passing trains in opposite directions will work a miracle, and their wish to be reunited will come true.