Kougekiryoku Kyokuburi no Saikyou Majutsushi: Kinryokuchi 9999 no Daikenshi, Tensei shite Nidome no Jinsei wo Ayumu

Uranus was once a legendary warrior who fought alongside the Hero's party to save the world. Three centuries after that great battle, he finds himself reborn as Agil, the son of a noble family—while mysteriously retaining all the power and abilities from his previous life. Now living in a peaceful era, Agil chooses to honor his parents' wishes by pursuing a path as a court magician and enrolls in the prestigious Hero Academy. With his extraordinary abilities far surpassing his peers, he navigates the challenges of academy life while keeping his true identity hidden. As he begins his new journey, he encounters various students and faculty, each with their own secrets and stories, setting the stage for a new chapter in a world that has long forgotten its greatest heroes. (Source: Overlap, translated)