When the Japan Coast Guard investigates an abandoned yacht in Tokyo Bay, their boat is destroyed and the Tokyo Bay Aqua-Line is flooded. After seeing a viral video of the incident, Deputy Chief Cabinet Secretary Rando Yaguchi theorizes that it was caused by a living creature. His theory is confirmed when news reports show a massive tail emerging from the ocean. The Prime Minister assures the public that the creature is unable to come onto land due to its weight, but it moves inland via rivers and makes landfall. It moves through a coastal city, leaving a path of destruction and numerous casualties. It evolves into a red-skinned form that can stand upright on its hind legs, however it begins to overheat and returns to the sea.