In "Death Note," the consequences of seeking justice at any cost are portrayed through the character Light Yagami, who gains the power to kill anyone by writing their name in a supernatural notebook called the Death Note. Initially, Light believes he is using the Death Note to bring justice to the world by targeting criminals and wrongdoers. However, as he becomes consumed by power and begins to bend his own moral code, the consequences of his actions become more severe. The series explores themes of morality, power, and the impact of seeking justice through extreme means, ultimately showing that the pursuit of justice at any cost can lead to corruption, loss of humanity, and unintended consequences.