Kei Nagai dies in a car accident, but realises he is a type of immortal known as Ajin. Hunted by humans, Ajin is eventually found by the government and used as a subject in cruel experiments. He finds fellow demi-humans along the way as he escapes and goes on the run.
Set in the year 2020, following her supposed death, a young woman returns as the son of her noble family to precede the family's prestigious company, with a demon at her side to avenge her parent's murder.
Kei Kikuno attends a vocational school as a student. For her part-time job, she works as a contract killer. She is excellent at her job and never gets scared by anyone. One day, she receives the most challenging request.
