Behavior Analysis (Assassination Classroom x ???)

Y/n shows up with professor Bitch as a top ranking assassin and classmate. Instinct and behavior are key to assassination, he just happens to specialize in that. "The devil's Revenge", the name of his blade, capable of leveling a small mountain if used right. he keeps many secrets and the origin of his blade is one, how it has never broken? how it folds up so clean? How it weighs less that that of a dinner plate? But will they figure out the secret before their lives conclude?