Light Yagami's actions, particularly his descent into moral ambiguity and obsession with power, have a profound impact on the psychological well-being of those around him. For his family and friends, such as his sister Sayu and his childhood friend Ryuzaki, they experience shock, confusion, and betrayal as they witness his transformation into the manipulative and ruthless character known as Kira. Their relationships with Light become strained, leading to feelings of fear, guilt, and helplessness as they try to come to terms with his actions. Additionally, characters like L and Misa Amane are directly affected by Light's behavior, with L engaging in a high-stakes mental battle with him and Misa developing an unhealthy dependence on him. Overall, Light's actions create a web of psychological turmoil for those in his orbit, ultimately highlighting the destructive nature of his pursuit of justice through immoral means.