A girl is guilty for what she has done and is determined to tell her parents but she doesn't know how to and how they will react.. what do you think she has done?

This story takes place in the future where Nagisa is an Assassin and hasn't seen anyone from class E3 in years. I'm open to any criticism and ideas on how the story should go. Please enjoy my fist ever story! Just so you know there isn't immediate romance, the Nagisa and Karma tension is just a plus! ( This isnt smut just you know, idk if i wanna put any in there)