Dr. Furuhata moves to the remote White Sands Village. There is no path from the road to the village, which, itself, is broken down and badly maintained. All the inhabitants look pale and sickly, including the village chief; and Furuhata believes he's witnessed a mysterious tremor in the trees.
Furuhata begins working at the local clinic with a nurse as his assistant. Although she is ostensibly a young woman, she too resembles a skeletal corpse. The village's only water supply is from a well that sometimes turns red. Furuhata is told that because the village is so isolated there is a lot of inbreeding, thus, most of the people have hereditary anemia. The villagers also all have type AB blood.
The next day Furuhata encounters a young girl who is copiously bleeding for no apparent reason. The villagers tell him that it is very common for them to start bleeding like this. Furuhata arranges to take a sample of the girl's blood and to send it to a colleague for testing. Out in the village he notices that there is a large amount of blood where a tree was uprooted during a storm the previous night; but can't imagine anyone surviving that kind of blood loss and thinks it must have been a bear.
Riyo Sunagami, whose sister was the little girl mysteriously bleeding, comes to have a blood test in her sister's place. Soon, Sunagami begins to recover. She tells Furuhata that young people recover quicker but then they bleed again and become pale and corpse-like once more. Furuhata notices tremors in the trees again, and that the water tastes as if it's been mixed with blood. While he is out walking at night, Sunagami asks him to follow her to a shrine. He believes the tremors seem to be coming from the shrine.
Sunagami says that local legend has it the shrine once accepted blood sacrifices from young women so, when she has enough blood in her body, she goes there to make wishes. Her wish tonight is to spend her life with Dr. Furuhata. Before Furuhata can stop her, she cuts her wrist, and begins hemorrhaging from her entire body. Although she should have died from the blood loss she survives, and, returned to a corpse-like state returns to the village alone. The ground absorbs her blood very quickly.
Furuhata begins digging under the shrine and discovers that underneath it is a living vein of human blood - type AB, as he finds when he tests it. He deduces that all the villagers' blood is being sucked from them and absorbed into the vein. The tremor he'd heard was its pulse, which is coming from the source under the shrine. To prove it, he stabs into the vein with his shovel; but the villagers begin hemorrhaging rapidly to compensate for the loss. Furuhata rushes to stop the wound but is halted by his own blood loss, and collapses.
Shortly after, Furuhata's fellow doctors whom he had told about his experiments with the blood arrived to help him. They are horrified to see that he has become a walking corpse like the villagers.