https://mechacomic.jp/books/254641

https://mechacomic.jp/books/258723

“In a world where someone like you is at the bottom, your thesis isn’t even worth reading.” In a society where the strength of your innate skill alone decides everything, Kazuki Shindō, who possesses only the weakest skill, falls with no chance to turn things around and ends up living in an alleyway. He believes the world would change if only his research were recognized—but that hope is crushed when he dies in a back alley before achieving anything. When he next comes to, he has regressed seventy years, back to his student days, still retaining all the knowledge and techniques of “Tuning,” the life’s work of his research. “With this… I can change everything.” From that day on, his life—and the world around him—are completely transformed. Branded trash who can only use the weakest skill, he smashes those scornful expectations with sheer ability and claws his way up through the ranks of an academy where talent is everything.