Toaru Majutsu no Index - Volume 21, Chapter 6: The True Darkness Unfolds. Up_the_Castle.

A college student was returning home after studying abroad for several years when the end of the world happened. A dragon appeared out of nowhere and attacked the plane he was in, thanks to an incredible amount of luck and his quick-thinking, he managed to survive the plane crash only to get stuck on a tropical island. A weird system took over the world and brought monsters to Earth. While nations collapsed and the world as a whole was being destroyed by ridiculous monsters, Leon was stuck on a godforsaken island with no chances of being rescued. What will happen to him? How will the world change while he is away? Will he even manage to return? The story, all names, characters, and incidents portrayed in this production are fictitious. No identification with actual persons (living or deceased), places, buildings, and products is intended or should be inferred.

Dr Dalton Wyatt, a world renowned Scientist and Inventor is transmigrated to the body of a high school student Dalton Wyatt who committed suicide due to unfortunate circumstances and complicated life.