Restricted is a game set in an abandoned mansion on the outskirts of London, where Lonely Cardia lives isolated from the world. Her body carries a deadly poison that destroys anything she touches, with the locals calling her a "monster." Her last conversation with her father two years ago is the most distant memory she has. One day, her quiet solitude is disrupted when the royal guards come to capture her. Then, Cardia meets Arsene Lupin, a chivalrous thief, who helps her escape from the soldiers. Soon, they embark on a journey to find her father, who holds the answers to her mysterious condition. Along with four other interesting and handsome men, their adventure is just beginning.