Soul of a young boy re-incarnates into the body of a new born noble devil from the House of Beleth of the 72 Noble demon house. At the age of 5 year old he awakened [Infinite Anime System] that grants him ability to travel and experience multiple Anime world and bring characters from those world's to become his servants.
Read: How the boy becomes the master of Underworld with his knowledge and [Infinite Anime System].