He is portrayed as a brilliant but bored genius who finds the Death Note, a supernatural notebook that allows the user to kill anyone by knowing their name and face, after it is dropped by the Shinigami Ryuk.

Frustrated by the status quo and unfairness of the world, Yagami uses the Death Note to kill those whom he deems morally unworthy of life, masterminding a worldwide massacre as the serial killer Kira (キラ).

[3] Over the course of his efforts to create a world free of crime, wherein he would rule as a godlike figure, Yagami is pursued by law enforcement groups such as the NPA and a world-renowned detective named L. In the anime adaptation, he is voiced by Mamoru Miyano in Japanese and by Brad Swaile in the English version.

[4] Takeshi Obata, the artist of Death Note, said that he had "no trouble" designing Light as the character description presented to him, "A brilliant honors student who's a little out there," was "clear and detailed".

[10] Kaneko designed Light's room to reflect the character's personality by making it clean and neat and filling it with legal, criminal history, foreign, and academic books.

[13] He is portrayed as a teen genius and a model student with a polite, reserved, and gentleman-like personality, who is well-liked and popular among his peers and teachers and known for being the class topper.

His father, Soichiro Yagami, is the chief of the National Police Agency, and is the head of the task force hunting for "Kira", the name the public has given to the perpetrator of a string of inexplicable murders around the world.

While his agenda originates with good intentions,[16] Light eventually finds himself killing law enforcement and even innocents in order to elude capture.

It is during this time that Light reverts to his original persona: a caring, level-headed, and empathetic individual unwilling to manipulate others or commit or justify acts of crime, such as murder.

Over four years later, Light is able to garner most of the world's support, reaching the point where his followers have begun to worship Kira as a literal deity.

Near heads the SPK (Special Provision for Kira), an American investigation team composed of CIA and FBI agents, while Mello works with the Mafia.

Seeing that Light has finally lost, he is killed when Ryuk writes his name in his own Death Note, just as the Shinigami had warned when they first met.

In the films, he is portrayed as a distinguished, popular and intellectually gifted college student, who has a disregard and frustration of the incapability of the law enforcement system to quell the rampant increase in criminal activities around the world, which drives his motives to use the Death Note, to change the world into a utopian society without crime, under the alias of a god-like vigilante known as "Kira", much like his manga counterpart.

Light's motives also slightly differ; in this version, he uses the Death Note mainly out of his frustration from the perceived failures of the Japanese justice system.

Light, prior to his discovery of the Death Note, hacks into the national police database and finds that the government is unable to prosecute many criminals, either due to lack of evidence or technical loop-holes, among other reasons.

Also, Light discovers the Death Note in an alley during a rainy night after encountering an acquitted felon named Takuo Shibuimaru in a night-club.

Rem, knowing that L's actions will reveal Misa's identity as the second Kira, writes both L and his handler: Watari's names in the Death Note.

Light dies in his father's arms, begging him to believe that he acted as Kira to put the justice, which Soichiro had taught him since his childhood, into practice.

A mid-credits scene reveals a video recorded by Light addressing the film's events to have occurred just as he has expected them to, teasing his potential resurrection.

The information obtained from their deaths is relayed to the police task force, who ambush Light in a warehouse in a sting operation led by L's successor Near.

[26] According to Ohba, Light sees Misa Amane, whom he uses as an accomplice, as a "bad person" who killed people, so he acts emotionally cold towards her and manipulates her, although he pretends to love her, and even says he will marry her.

[27] Although Light, bearing love for his family and "humanity as a whole", originally had good intentions to transform the world into "a better place", he was also "very conceited", with a "warped ... desire to be godlike".

[30] Douglas Wolk of Salon describes Light as "coldly manipulative", "egomaniacal", and "an unrepentant serial killer, a butcher on an enormous scale" who is not "a Freddy Krueger, a monster who represents pure evil, or a Patrick Bateman, a demonic symbol of his age".

[34] Wolk describes Light's ideal world, a "totalitarian" place "ruled by a propagandistic TV channel and an arbitrary secret executioner".

[31] Jolyon Baraka Thomas describes Light's vision of justice as "impure": "[His] supercilious attempt to save society from itself is both self-aggrandizing and cruel".

[41] Jason Charpentier of The Anchor stated that Light's attributes and his role as a main character form "part of what makes Death Note interesting".

[43] In 2014, he was placed seventh on IGN's list of greatest anime characters of all-time, with the cite stating that "Light Yagami was the force that drove Death Note and made it a phenomenon".

[44] Manga artist Katsura Hoshino, a former assistant of Takeshi Obata, has said that she likes the way that Light is often drawn as he gives the appeal of a cool villain.