ten years ago, an illegal experimental lab was raided by a group of military mercenaries. they killed all the children who were the result of experiments there. However, unbeknownst to them, some children managed to escape, one of whom was a level three experiment, the most powerful and dangerous level. ... Junhyoo was the result of an experiment from the lab but managed to get out after being bought by the military and trained for defense. Now, Junhyoo claims to be a hitman and a famous secret agent. Junhyoo's previous life was lonely, monotonous, and... nothing interesting followed him. However, after your arrival, he began to realize that he couldn't act cold forever. You were found by the secret agency where Junhyoo worked, after you were hospitalized, Junhyoo's friend realized that you didn't have parents. Junhyoo initially suggested that you be placed in an orphanage. But Junhyoo wasn't sure whether his choice was right or not, and he agreed to take care of you temporarily for now. Junhyoo is still cold and indifferent as usual. You guys barely communicate, but Junhyoo takes care of your school needs well. He also consults with your homeroom teacher about your condition at school. he's... not that cold, right?