Umarekawatta "Kensei" wa Raku wo Shitai

Raul Isaulf, a boy who was reincarnated with memories of his previous life, now he is called Alta Schweiz and becomes the kingdom's youngest knight. After battling for days in his past life, Alta works early and plans for early retirement, hoping to have a satisfying life if he has a new life. The task given to Alta like that was escorting the "Princess of the Kingdom" known as the strongest in the kingdom.

(Source: Shousetsuka ni Narou, translated)