An exceptional marksman and hopeless playboy, private eye Ryo Saeba reluctantly forms an alliance with his late partner's sister to investigate his death.

The film's story poses the possibility that all of humanity, without exception, live in two worlds of existence: the real world and a second world known as "Hemu". Humans live their lives in Hemu when they sleep in the real world. Hidden in each person is another life of which he or she has no recollection of, except for nightmares which are soon forgotten upon waking up. However, there a few rare individuals who are aware of the existence of Hemu and the curious consequences it has on the real world.