Huh. I'm still a little puzzled about just what Princess Lily's motivation is, but it seems to be something about her mother's death.
Not much to say about her beside what's already been said, but...yeah. She's a sociopath, and, worse yet, a high-functioning one. Tomoki is a tool in every sense of the word, and guns...oh boy. Guns.
There's the obvious destructive impact on the world their implementation will have and Tomoki is a fuckwit for not thinking of that, but before that, is it even true that kids and the elderly can use them? I assume their kickback would have to be pretty strong-especially if they need to be high-caliber enough to down monsters and pierce barriers.