The Brain Flower Saves the World

[Full title: I Was Reincarnated as a Brain, and My Goal Is to Save the World. It's Too Long, So I Cut It Down to This] An ordinary high school student is tricked into becoming a savior, only to be reincarnated as the final boss in someone else's story. What should they do? Kishitani Tsuki decides to be true to herself, no matter what identity she has. So what if all that's left of my original body is a lump of brain? So what if I'm now stuck bringing along a deadbeat pretty-boy curse user assassin boyfriend by default? So what if I'm pretending to be the leader of a shoe cult, with a mysterious organization's top brass around me, and the emperor of part-time jobs, whose identity as a cop I've known from the start? If I want to change this world, I think I can, and I will. No couples in this story. Everyone's relationship is platonic. The settings of Jujutsu Kaisen, Detective Conan, and Bungo Stray Dogs, with Jujutsu Kaisen as the main focus. I don't know enough about the police academy group, so they won't be involved. A small amount of Katekyo Hitman Reborn content. The male lead uses Fushiguro's mother's body in the early story (after Megumi's mother died, Toji found a rich woman willing to marry into his family). He will change bodies later. There is a pregnancy plotline (the brain's body comes with it), but no childbirth. Theme: Stay optimistic no matter what your circumstances are.