Saikyou Rakudai Kizoku no Kenma Kiwameshi Antou-tan

Roy Luvel is a minor nobleman from the outskirts of a small country. He's a poor student at the academy, earning him the nickname “The Failing Noble.” However, he harbors a certain secret. "The Guardian of the Sword Nation, the White Sword Master, Cloud" "The Guardian of the Magic Empire, the Black Grand Sage, Eclipse" The true identities of the most admired heroes in these two great nations are none other than Roy, who is only pretending to be incompetent! To protect his family, Roy hides his identity and leads a triple life, secretly working in each country while enjoying freedom at the academy. Moreover, he catches the interest of the beautiful girls at the academy who aspire to become swordsmen and sages… Roy’s extraordinary daily life is fiercely intense! “I’d love to quit being a guardian, but until I find a successor, I guess I’ll have to keep on saving the world.” A grand fantasy about the clandestine nobleman who has mastered both sword and magic begins here!! (Source: Web Ace, translated)