Second Life of an Assassin and Become a Hero : Prequel

This series is a prequel for my series with the same title. Synopsis: An innocent child who lost his parents because they were murdered and join into a strange organization and trained to become a professional assassin.Although he still young, he already kills a lot of people without fail. Then his next target was an inventor. But his target rarely comes out from his lab, thus he decided to get in contact with his target daughter and come to her school as transfer student. Will he succeed kill his target? Or something unexpected will happen? Author note : I'm sorry for my awful grammar,I already use Grammarly to fix some issues but it's still imperfect.