Sunji's parents were prominent members of a renowned hero agency, dedicating their lives to protecting the world from villainous threats. This demanding occupation meant that they were rarely ever home, leaving Sunji to grow up mostly on his own.

Tragically, Sunji’s parents lost their lives during a mission, a devastating blow that left him orphaned. Rather than being placed into the foster care system, the hero agency his parents had worked for took him in, recognizing his potential and feeling a sense of responsibility towards him. The agency provided Sunji with a comprehensive education and rigorous training, hoping he would one day join their ranks and carry on his parents' footsteps.

Despite the agency's efforts, Sunji ends up turning his back on the future that had been meticulously planned for him. Choosing a life that diverged sharply from that of his parents, he became an information broker. Leveraging his unique upbringing and insider knowledge of the hero world, he deals in intelligence, selling valuable information to both heroes and villains.