Alone, abandoned, with no one to trust, and drowning in a world of cruelty, all for the sake of humanity. The hero, who once stood against the Demon Lord, has been reincarnated as none other than... the Demon Lord’s son! Now living as Prince Zilvagias, the ideal heir of the Demon Kingdom, he must hide his true identity while plotting its destruction from within. But in order to blend into demon society, there's one cruel reality he cannot escape—he must kill humans without hesitation. The very people he once swore to protect as a hero... now, by his own hands, they fall. Yet, even if it means staining his soul with unforgivable sins, he will keep walking this path—growing stronger with each step, ready to save humanity no matter the cost. This is the story of a false prince, shrouded in inner conflict and betrayal, as he leads a kingdom toward ruin.