He also could barely contain his laughter during his final confrontation with Near when he thought that everyone in the room would die, demonstrating the sadistic pleasure he took in their deaths and his would-be victory. Such an instance is seen when he kills Naomi: after she prepares to commit suicide, Light mockingly tells her that his father's cellphone is available while smiling, solely doing this for pleasure. He is also shown to be a sadist though he is not explicitly aroused by the act of giving death, he is sometimes shown smiling devilishly, hinting at his vicious tendencies. A criminal mastermind, he often elaborated unbelievably complicated schemes to compensate for his lack of henchmen, involving pretty much nearly everyone around him. He was also able to fool Takada, a much more clever woman, into being his “queen” and thinking that he loved her, when it turns out, like Misa, he only thought of her as a pawn, as seen he killed her without hesitation when the opportunity arose to kill Mello and to prevent her from revealing any secrets about Kira. He was able to convince Misa that he cared about her and that he was grateful for everything that she'd done for him when he only thought of her as a pawn which he'd kill once she outlived her usefulness. He is an extremely clever, psychopathic and sly master manipulator who can easily act as an innocent and friendly individual in public who would never kill someone, while secretly killing dozens or hundreds of people each night. He even planned to kill unhealthy or lazy people once he became a God in order to build a strong, disciplined utopian society based on a eugenics ideology, even though he did not hold supremacist views. He has a self-centered personality, as he created the identity of Kira in order to lead a cult devoted to himself, even though his followers were unaware of him being their savior. Light is an unfeeling madman who is only driven by his immense hatred of criminals and is ready to do anything in order to become nothing less of a living deity.
~ Light Yagami trying to convince Matsuda to kill the others. In this world, all those earnest people like him fight for justice! They always lose! You want a world where people like that are made to be fools?! I know you understand, so kill the others! Shoot them! It is upon discovering the Death Note and seeing its deadly effects, that Light went mad with its power while believing himself to be the "chosen one" who would eradicate all the people he considered to be evil and become the God of the new world (even after Ryuk explicitly stated multiple times during the story that he randomly dropped the book somewhere in the world). However, even then, he agreed with the principles of "Kira". He regained his old personality upon giving up ownership of the Death Note. Light did not start as a murderous vigilante - he was a sympathetic and popular, yet depressed student who was bored with his life, with real concerns about fixing the world of its various injustices, and believed that the world was "rotten" because of the evil people in it. In the anime, Light was voiced by Brad Swaile in the English dubbed version, and Mamoru Miyano in the Japanese version. It also demonstrates his evolution from a noble extremist into a sociopathic mass murderer.
The series charts Light's use of the notebook and his struggles with the Japanese police, the detectives L, Mello, and Near, as well as his associations with other notebook users, such as Misa Amane and Teru Mikami. Although Light got most of the world under his control, his reign came to an end when he got cornered by the Japanese police, and eventually, Light died of a heart attack when Ryuk wrote his name in his Death Note. Obsessed with his goal, he used and even murdered a lot of innocent people.
Throughout his journey, he globally became known as "Kira" (a mysterious figure who anonymously murdered criminals) and continued his work for the next few years, while trying to evade capture. In addition, he was being accompanied by the notebook's original owner- shinigami Ryuk. After realizing that it worked, Light decided to use the notebook as a murder weapon to eliminate all crime and create a utopia with only the law-abiding people he accepts, and make himself the God of this new world.
Initially skeptical of its abilities, Light tested the notebook on two criminals. Light was a Japanese high school senior who found a Death Note, a mysterious notebook that would kill anyone whose name was written in it. Light Yagami is the villain protagonist of the Death Note manga/anime series, as well as its multiple adaptations. And I… I will become the God of this new world. I'm a hardworking honors student who's considered to be one of Japan's best and brightest.