In "Death Note," the theme of the abuse of power is explored through the protagonist, Light Yagami, who gains the power to kill anyone simply by writing their name in the Death Note. As Light becomes consumed by his newfound ability and begins using it to carry out his own sense of justice, he starts to abuse his power by deciding who lives and who dies, essentially playing the role of judge, jury, and executioner. This abuse of power leads to consequences and raises questions about the ethical implications of having such control over life and death.