Isekai Kita no de Mahou wo Sukebe na Koto ni Riyou Shiyou to Omou

A young boy, summoned to another world for the purpose of defeating the demon lord, used all of the power at his disposal for the sake of said world. With the reliable knight corps by his side, he defeated the demon lord, and by the time that peace had come to the world, the young boy had grown into