Starting My New Life as a Demon Kid

The story takes place in the world of "Human-Demon Chronicles," where angels and demons wage an endless war. In an age when the balance of the world was hanging by a thread, Johann was reincarnated as a half-human, half-demon born from a human. He must sometimes suppress his emerging demonic instincts and sometimes make use of them, manipulating the characters of the novel and punishing its villains... as a demon should. The whispers of demons are harbingers of doom. If you heed their words long enough, you may one day find yourself standing on the brink of ruin. However, there's one whisper that's different... Johann’s. (Source: Naver, translated)