My Past Life is a Divine King

A high school loser just remembered he used to rule the universe. There's one problem: he's currently powerless, broke, and every time he tries to cast a spell, people film him for acting like a weirdo. But when he starts hot-wiring modern tech—using a smartwatch to track his "mana," buying herbs on the Internet for forbidden pills—he realizes the ancient way might just need a modern upgrade.