EIYUU TO KENJA NO TENSEI KON

Eiyuu to Kenja no Tensei Kon summary:

Reid, a young hero with the strongest physical strength, and Elria, a beautiful sage with the strongest magic prowess.
They continued to fight as rivals in opposing enemy nations, but their relationship came to an end with the sudden death of Elria… Then, a thousand years later,
Reincarnated in a world where magic reigns supreme, but he who has retained the strongest physical strength from his previous life, Reid, was reunited with Elria, who has also been reincarnated―
“Hey, Reid— I want you to marry me.”
“…Huh?”
The two, who have become the strongest unaware lovey-dovey couple in a thousand years, enrolled in the Royal Magic Academy to decide who is stronger!

Reid, a young hero with the strongest physical strength, and Elria, a beautiful sage with the strongest magic prowess.They continued to fight as rivals in opposing enemy nations, but their relationship came to an end with the sudden death of Elria…