Its a isekai story about Reiki Delta a man who was your average man, but was reincarnated after dying a mysterious death. Reiki is seen as a child prodigy making his own powerful spell Hell Flame at the age of 5!! It follows Reiki who partners up with adventurers and form a party known throughout the world as the GateKeepers! Reiki is the Child of prophecy the Celestial, he is destined to save the world from a ultimate evil who appears every thousand years, this evil is only known by the title of "The Devouring Void: Harbinger of Oblivion" It is up to Reiki and the Gatekeepers to protect this world from the Harbinger.