From the introduction:
Welcome to a strange world of floating islands and continents over an endless sea, filled with magic, robots, adventurers and academies.
A world risen from the ashes of a massive war between the technologically advanced, and now extinct, Old Humanity and their many scientific wonders and the New Humans and their magical powers. Sufficient to say, the New Humans won against the Old Humanity replacing them and wiping them out, but their magic quickly degraded after that, and nowadays the still functioning relics of the Old Humanity have a power that far surpasses what the New Humans consider possible.
But the most interesting fact about this place is that it is almost identical to a certain Japanese dating simulator saga. And that several Japanese people, many of them with the knowledge of said games, have reincarnated around the same time in this world.