Saikyou Mahotsukai no Ai ga Ichizusugiru Fuinsareta Moto Seijo wa Kinki no Ai de Omezame desu

Condemned for treason on fabricated charges by the royal family, the saint Celica chose to seal herself away, fearing that the orphan Morte, whom she had rescued at the Demon King's castle, would be placed in danger once more. Ten years later—when Celica awakens from her long slumber, the person standing before her is Morte, who has grown into a completely different person from the boy she once knew! Source: MU