Known for his logical and composed approach and exceptional negotiating skills, Koujirou Shindou is a highly respected government official. However, during a routine business trip, his airplane is swallowed whole by an impenetrable cube, which leaves the passengers unscathed but bewildered. As Japanese authorities search for answers about the mysterious cube, Shindou encounters Yaha-kui zaShunina, a being from a higher-dimensional realm who has taken human form. Despite the strange circumstances, Yaha-kui zaShunina assures Shindou that the passengers are safe and seeks his assistance in negotiating with Earth. Yaha-kui zaShunina, utilizing the cube known as Kado, exchanges information between universes to enhance humanity's progress, starting with Japan. Though possessing incredible abilities, the being poses no discernible threat, focused solely on humanity's advancements.