Assassination, escort, intelligence, apprehension ―― Tweight, the ace of the “agency” in the dark side of kingdom, undertakes all the dirty work for country and supports the Brave to subjugation the Demon Lord from shadows. In the end, Tweight will get more and greater achievements than the Brave and become the “Shadow Hero”, known to everyone. The Agency will be dissolved after the Demon Lord is defeated. Tweight gets a recommendation from his boss. Since he was brought in by the agency when he was a child, Tweight, who has never lived an ordinary life, wants to enjoy everyday life in the same way as ordinary people do. At a later time. On the recommendation of his boss, Tweight decided to register at Builder Academy, which is largest institution in the Kingdom. What awaits him there is the daily life he craves with his school friends who have unique habits. Even though the demon lord is defeated, that does not mean that the world has become peaceful. Inherited Demon Lord. Hostile organization. And pus from his own country. There are still a few conflicts in the kingdom. It was the beginning of an unstable era with all kinds of threats. The daily life he is looking for will be destroyed in a short time if he loses his calm. This is a story about an awkward boy who is a former “behind the scenes”. Fights, opposes, and tries as hard as he can to protect his daily life from him.