Light Yagami's interactions with criminals and victims in the anime "Death Note" are significant as they serve to showcase the moral ambiguity and complexity of his character. His interactions with criminals demonstrate his initial intention to rid the world of evil and create a utopia through his use of the Death Note. On the other hand, his interactions with victims highlight the consequences of his actions and the ethical dilemmas he faces as he grapples with the power he holds. Overall, these interactions help to portray Light as a complex and morally conflicted character as he navigates his newfound power and the implications of his choices.