When Natsuki woke up one day, he discovered that he'd suddenly turned back into an elementary school kid and transmigrated to a parallel world. He thought transmigration always came with a System, but the crazy System was late. In the years before it showed up, Natsuki kept trying to trigger it, and had long since become a chuuni in the eyes of everyone around him. At last, he thought he could climb to the top of life like an ordinary person, only for the late-arriving System to turn out to be a crazy System that makes his chuuni fantasies come true. (That's the normal synopsis.)
Actually, it's just a goofball meeting a crazy System and making the whole world go crazy.
Also known as From Exorcist to Regretting My Own Setting
