This story is about the summoned demon king. Ivan, the Demon King of Destruction was summoned by the goddess of light as a hero with other 14 people making them 15 including himself. The goddess didn't have much of a choice to summon Ivan as he has the power to turn–over fate. Luciel is one of the beings that can kill god's and he considered a calamity level threat, but he's kind hearted, and with that the saintess will forever turn him into a human, and giving him a blessing as promised upon summon. Hope you like this and enjoy