They've reclaimed the walls, beaten the titans and peace has returned. However, there is still hostility towards Eren. People fear he may be too much of a risk. The government refuses to kill him after saving humanity but ask that, for his life, Hanji is allowed to turn him human, or at least less worrisome. Levi and Hanji divised a plan to make him seem less of a threat but first, Levi gets to have his own fun after all these years,right?