The Lost Rebound are the closest people to those who become Kanshu or are killed by Kanshu. When Kanshu absorbs all the information of a person that they kill or infect, the people closest to them pass out and suffer mental damage that's equal to the bond between the killed/infected and the Lost Rebound. The phenomenon deals with the mind trying to make sense of the contradictions. Hatsumi Island has produced the largest amount of lost rebound victims due to unknown reasons seven years ago.