After Entering the Book, I Cut Off the Beards of All the Heroines

A modern high school student accidentally traveled into a campus novel he had read and became a delinquent boy from a well-off family but with a notorious reputation. He originally wanted to avoid all the female protagonists and live a low-key high school life, but due to the huge contrast with the original character, he unexpectedly disrupted the fate of all nine female protagonists in the novel - they were saved one by one by his knowledge and tenderness in the "future" (which is equivalent to more than ten years in the world of this novel). And the only thing he really cares about is his childhood sweetheart who has been heartbroken by his original self.