Light Yagami initially believes that his actions as Kira are justified and necessary to create a better world by eliminating criminals. He convinces himself that he is a righteous savior and uses the power of the Death Note to carry out his version of justice. However, as the series progresses, Light becomes increasingly consumed by his power and ego, leading him to justify more extreme and morally questionable actions in the name of his cause. Ultimately, Light's moral ambiguity becomes more pronounced as he becomes willing to sacrifice innocent lives and manipulate others to maintain his power as Kira.