Six years after the JS Incident, a young dimensional traveler Touma Avenir rescues a mysterious mute girl named Lily Strosek from a secret research facility on a distant world of Ruwella. When rescuing her, she gives Tohma an amulet that gives him access to a new Device power. However, unbeknownst to them, there is another with a similar Device causing massive damage and injury. Tohma becomes an unwitting accomplice in an incident involving the Book of the Silver Cross, an ancient Belkan magical tome, leading to an investigation by the Time Space Administration Bureau and the latest interdimensional crisis faced by the former Riot Force 6 members...