Nagisa Sensei: A New Assassination Classroom (adopted)

What happens when Nagisa goes to teach a bunch of delinquients? Class 3-5 recieves yet another teacher, but this time he stays and mixes assassination into the mess. He becomes respected, but what happens if they find out Nagisa's secret of his past? (Warning: swearing, mentions of abuse) -Inspired by <3Raoor!- -I do...