After some thoughts, MakiDen turns out to be not that bad ngl. Yes she was a psycho, but Denji is no better. And through Nayuta we can see that if Denji agrees to give her a happy family, she will just leave the world alone. Therefore if Nayuta returns with Makima's memories and becomes a couple with Denji, it will be a totally suitable ending for Denji desu