It has been six years since you escaped killua. He was super obsessed with you and wanted to kill you at the same time then. With you already escaped from him and was away from him for six years, he gone crazy mad insane. He started going back into an assassin. Being a psycho. Even so, he was still able to find a girlfriend in the meantime to replace you. You didn't know but was glad he didn't bothered you anymore. But you thought.

One day when you were back home from work, your door was opened.