In another world with my smartphone

The population of Brunhild is booming, which can mean only one thing. Guards, guards! We need more guards! A mass call is set out. "Knights Wanted: Apply Within!" But Touya might end up with more than he bargained for... Meanwhile, in the floating halls of Babylon, a certain resurrected doctor begins her mad machinations... Just what kind of crazy machine does she intend to build next? Set a chivalrous course for a tale of swords, sorcery, and burning sands!