The Tech Prince of Britannia

Before I went to hell I was offered a chance to live in one of my favorite worlds as long as I help the collective consciousness of humanity to not be destroyed by the Emperor. Well, at least I get two wishes before going. Now, how will this world behave when someone with unprecedented intelligence enters the stage? (SI-OC, mechas and other techs from other animes, AU with time, Harem accepting suggestions) . . Current confirmed members of the Harem: - Nunnally Vi Britania - Marrybel Mel Britania - Kallen Kozuki - Nina Einstein - Nemu Kurotsuchi (Bleach) three to four more options are open, tell me who would you like to add in the reviews