The rules of the Death Note, a notebook that allows its user to kill anyone by writing their name in it, heavily influence the characters' understanding of morality throughout the series. The main character, Light Yagami, initially believes he is using the Death Note for a noble cause - to rid the world of criminals and create a utopia. However, as he continues to use the Death Note and the rules become more complex, his sense of morality becomes warped. The rules of the Death Note challenge the characters to question their own ethics and the consequences of their actions, ultimately leading to a deeper exploration of right and wrong in the series.
