There are two time and spaces in this world, one is the time and space where human beings survive, and the other is the time and space where humans go after they pass away. This time and space is called the gray zone. The space gaps connecting these two time and spaces exist in various places in the world, and the people who guard the space gaps are called requiemers. The existence of the Requiem has not been known since ancient times. They mingle among the ordinary people and appear in the form of families. They are mainly responsible for guiding those souls who linger in the world and do not want to go to the gray area to leave. In addition to the Soul Eaters, there are Soul Eaters, who usually exist independently in human society. Help the Requiem Ones to deal with some souls and nightmares that cannot be appeased.