Thousands of years ago during a time of crisis, God sent down incarnations of himself that represented Sins. These Spirits of Sins kept peace and brought order to the world. Eventually, the spirits began to dwell inside a human body that is capable of being a host, these hosts were later on known as Carriers. After many events, the setting for When Promises End begins. After many years have passed since the Promised Day, Kazuya the protagonist in this story discovers he holds a powerful Spirit of Sin. As a Carrier, he learns that the fated Day of Corruption is near and he must stop it from happening. Otherwise the foreseen Apocalypse will occur once again. Source: When Promises End Store