Tokyo, 2017. The studious medical intern, Kei Nagai intent on saving his sick sister, dies in a traffic accident. However, moments later, his body is regenerated, and he comes back to life. Discovered to be an Ajin, a part of an inhuman race that cannot die, Kei is pursued by the police and civilians thirsty for the bounty placed on Ajin, and is held captive in an Ajin research facility. There, he is subjected to inhumane experiments. At the facility, a mysterious Ajin named Sato helps Kei. Sato is a terrorist that massacres humans in order to achieve his plans to subvert the nation, and create a society where Ajin can live in Japan. Although Kei is an Ajin like Sato, he cannot share Sato’s ideals. Meanwhile, Sato begins his shocking bid for power. An endlessly repeating battle between two men who can never die. To where with the future of Ajin lead...?