The reincarnated protagonist wakes up not in a mysterious space with a goddess or in the castle of a historical kingdom, but in the ``Demon Castle'' where there are eight ferocious-looking demon lords.The protagonist was born into a demon kingdom inhabited by many demons and demi-humans, and was pessimistic, but surprisingly, the demon lords loved him like a real son, and the protagonist grew up quickly as the demon lord's hidden child. To go.Eventually, he uses the knowledge he gained on Earth to develop his own magic technology, ``Magic Language (Magic Code)'', and grows to become one of the strongest magicians in the Demon Kingdom.The main character is surrounded by many families and lives happily, but the demon kingdom is invaded by heroes who have received ``cheat'' from the goddess.Protect your new family ...