One day, monsters called "Troubles" appeared and started attacking people indiscriminately. They sometimes took human form, while at other times they looked like terrifying monsters. At the same time, humans known as "Traces" began to emerge. Although they were human, they possessed superhuman abilities. While they frequently fought the Troubles, many people viewed them as yet another danger. Yu Kamiyama was born a Trace. His power frightened his parents so much that they sent him away. Raised in isolation and apathy, Yu began hunting Troubles to train himself. One day, he was overpowered and nearly killed, only to be taken in by a human girl named Akane and her father. Yu did not reveal that he was a Trace, allowing them to believe he was an ordinary human orphan. For the first time, he had the chance to live with people who cared for him, seeing him as human rather than a monster. Could he protect his new family and prevent them from discovering his true nature?