Oh yeah, why must Promoters be more than 18? All things considered, Rentaro's still in high school.

And in terms of plot ideas...I could imagine that humans might be interested in some sort of reclamation project. As in...clearing 'outside' areas of Gastrea and slowly expanding the territories of mankind. That might be something to go off. Alternatively, you could have a plot point through...cult/psycho groups specifically targetting things that would harm Cursed Children? Such as killing them, or blowing up stores filled with that vaccine they need to take daily, or by revealing Cursed Children that are trying to pretend to be normals. Stuff like that, I guess. Are we using the same Tokyo area? Or are we going to be elsewhere?