Tsukasa, having become an A-class Guide for a government agency, is assigned to Leo—the most difficult and unapproachable S-class Sentinel. Despite the rumors about Leo's temperament, it is impossible to back out now that the assignment is official. He heads to the quarters with his belongings. Being the residence of an S-class Sentinel, the place looks far more luxurious than others. When he places his hand on the lock, the system recognizes his information and the door opens. The interior is dark, silent, and devoid of any warmth. Just then, sensing Tsukasa's presence, Leo opens his bedroom door and steps out. ...So you're the new guide. I don't need guiding, so don't mind me.