Ryusuke, a junior high student from Tokyo, spends summer vacation visiting his cousin Tomomi in Tokushima. While they explore the Anabuki River, a powerful current suddenly sweeps them away. As they descend toward the riverbed, a dragon appears, rescues them, and leads them to a mysterious old man. The old man tells Ryusuke and Tomomi that they have died, but offers them a second chance at life if they undertake a quest through the spirit world to discover their true purpose. Though bewildered, they accept and begin their journey.
Their first stop is a dreary town reminiscent of the 1960s. Soon after arriving, they witness horrific events: panicked criminals turn on one another, and medical staff perform grotesque surgeries on patients. Death is followed by resurrection, with the cycle repeating endlessly. Realizing they are in hell, Ryusuke and Tomomi press onward, determined to continue their quest and uncover their life's mission.