Kougekiryoku Kyokuburi no Saikyou Majutsushi: Kinryokuchi 9999 no Taikenshi, Tenseishite Nidoume no Jinsei wo Ayumu

Uranus was a great warrior belonging to the Hero’s party which saved the world. Three hundred years later, he was reincarnated as Agil, the son of a local lord—all while keeping his past level and stats. A proud warrior in his past life, he decides to fulfil his parent’s expectations of becoming a court magician and enrols into the Hero Academy. With his overwhelming stats, he easily passes the difficult entrance ceremony and successfully enrols into the academy. There, he found that his roommate, Shanon was actually a girl disguised as a boy. Furthermore, she was in fact his past comrade, Luka the Hero—!?

(Source: Overlap, translated)