In Death Note, the protagonist Light Yagami initially believes that using the Death Note to bring about justice and eliminate criminals will not only benefit society but also bring personal satisfaction and a sense of power. However, as the series progresses, it becomes clear that Light's pursuit of justice is tainted by his own ego, desire for control, and ultimately his descent into megalomania. The show highlights how the concept of justice can be twisted when it is used as a tool for personal satisfaction, ultimately leading to destructive consequences.
