Light Yagami's actions in the anime "Death Note" have a significant impact on society as a whole. By using the Death Note to eliminate criminals, he initially garnered support for his supposed mission to create a utopia free of wrongdoing. However, as he delves deeper into his power and becomes more consumed by his desire for control, his actions lead to fear, paranoia, and a breakdown of trust in institutions like the police and justice system. This ultimately creates a sense of unease and unrest in society, questioning the morality of taking justice into one's own hands.