Tensei Akuma no Saikyou Yuusha Ikusei Keikaku

After two thousand grueling years in the infernal abyss, a former Japanese man who was reborn as a lowly devil has defied all expectations, amassing immense, unparalleled power. Despite his monstrous strength, his existence has been one of ceaseless struggle and harsh survival. When he is unexpectedly banished from Hell and cast into a vibrant new world, he believes he has finally found his salvation. Liberated from the endless torment of his past life, he settles into a quiet, humble village, cherishing the simple peace and slow rhythm of a world that asks nothing of him but his presence. However, his fragile paradise is shattered when a brutal assault descends upon the village he has come to call home. Rushing to defend the only sanctuary he has ever known, he arrives too late, finding only smoldering ruins and the lifeless bodies of his neighbors. Amidst the devastation, he discovers a single, miraculously surviving infant named Alus. Grief-stricken and burdened by a profound sense of guilt, he makes a solemn vow. To atone for his failure and repay the debt he owes to the kindness he was shown, he dedicates his eternal existence to one purpose: raising this child to become the happiest person in the world, no matter the cost.