Sousuke Sagara is a professional soldier, practically born and bred on the battlefield. A military specialist for the secret organization MITHRIL, he has just been given perhaps his most challenging assignment yet. Why’s it so challenging? Because it’s not a combat mission. For the battle-hardened Sagara, he now has to become accustomed to a new, alien environment…high school. Assigned to watch over and protect Kaname Chidori, a “whispered” candidate for MITHRIL, Sagara must ensure her safety and well being, fend off the enemies of his past, and try to do something he never had to do before: live the life of an ordinary teenager.