Clevatess - Majuu no Ou to Akago to Shikabane no Yuusha

After killing the wicked beast, the king, and the heroes, it discovered the "infant of fate." Such is Clevatess, king of the devil creatures, possessing both high knowledge and devastating might. He intends to destroy humanity out of rage at the 13 heroes sent to his murder, but instead he is given an unexpected burden: a newborn human child. Is it the journal of the new age of childcare or the story of a world on the verge of apocalypse?