Aoyagi Masamune doesn't lead an easy life. When trying to commit suicide by jumping from a rooftop, he instead gets pushed down by a young man called Kikuchi Hiro. Masamune survives and, when confronting Hiro, soon finds himself deeply involved with a cloning experiment from nineteen years ago. Eleven clones with different looks and gender were created at that time, now dying one after another. Masamune soon understands that each time two of them meet, they'll have to kill each other, since two people with exactly the same genes cannot exist at the same time. When he realizes that Hiro, himself and his childhood friend Marika are part of the group as well, he tries to find the people and the purpose behind the experiment to stop the killing.