ne day, a train explosion occurs on Kyu Morozumi's way to cram school. Since the explosion, adults have been dying one after another. Their deaths are all strange; they utter odd things before spitting up blood and dying. It seems to be an infectious disease of unknown cause that has spread throughout Yokoura City due to the train accident. Kyu's mother also becomes infected and collapses. He is helped by his classmate Naoki Mori and Yoko Hasebe, whom he meets in town, and tries to take his mother to the hospital, but it is too late.