In "Death Note," the protagonist Light Yagami initially believes he is using the Death Note to create a world rid of criminals, intending to bring about justice. However, as he continues to use the Death Note to punish those he deems unworthy of living, he becomes consumed by power and his sense of justice becomes twisted. The series showcases how the pursuit of justice can lead to corruption when one believes they have the authority to decide who lives and who dies, ultimately blurring the lines between right and wrong.