Histoty

In the year 2003 (2006 in the anime), Light Yagami discovers a mysterious notebook on the ground at his school. Written on the cover: the words "Death Note". The Death Note's instructions state that if a human's name is written within it, that person shall die. Light is initially skeptical of the notebook's authenticity, but after experimenting with it, Light realizes that the Death Note is real. It is in this way that Light Yagami found his true purpose in life: to become Justice by judging and killing all criminals with the Death Note. Light feels that he is the only one fit to judge humanity, thus he decides to create a New World where he alone is "God." After meeting the previous owner of the Death Note, aShinigami named Ryuk, Light seeks to control the world with Divine Rule, passing judgment on those he deems to be evil or those who get in the way of his goals.

A short time later, Light sets to work ridding the world of criminals, attracting the attention of the master detectiveL. Light and L encounter each other in several different battles of wit and logic throughout the first arc of the series. Once the second Kira, Misa Amane emerges, L is able to corner them both. After giving up the Death Note briefly to clear their names, Light is able to manipulate Rem into saving Misa's life. Kira's goal: to kill L, antagonist and arch-rival to Kira. When L is attempting to test the Death Note, Rem realizes that Light has trapped her. She is forced into a situation where she must choose: the life of Misa Amane, or her own existence as a Shinigami. It is only then that Rem has an epiphany: Light Yagami has surpassed all Shinigami, having the ability to even kill "immortal" Shinigami. Rem kills both L and Watari, and then dies, leaving her Death Note at Light's disposal.

With L dead, Light takes up his mantle in order to hide L's death from the world, becoming the second L while also putting him in the perfect position to continue killing criminals as Kira. He comes into contact with L's true successors, Near and Mello, who are out for revenge in the name of the true L: Mello wants Light dead, Nearwants him exposed as Kira. After making a mistake in using Teru Mikami as a proxy, Near is finally able to corner Light. Having decided that it is time to end Kira's game, Ryuk decides to kill Light.

In the Spring of 2004, Light becomes a first-year student (freshman) at To-Oh University, becoming one of two freshman representatives; L is the other freshman representative. During a tennis game with L at To-Oh, spectators reveal that Light was the junior high school tennis champion in 1999 and 2000; After his 2000 victory, Light quit tennis as he entered high school.

When L is finally able to corner him, Light puts his master plan in practice. He temporarily gives up his Death Note to Ryuk, erasing his memories about his time as Kira from his mind. Rem, under instruction by Light to give it to someone who would use it selfishly, gives it to Kyosuke Higuchi of the Yotsuba Corporation. Now unaware of the fact that he was the original Kira, Light accepts L's offer to join the investigation team to hunt down Higuchi, known as the third Kira. Light requests the alias "Light Asahi" to be used for him. When Higuchi is finally captured, Light touches his Death Note, thereby regaining his memory of when he was the original Kira. He then proceeds, exactly as planned, masterfully killing Higuchi by using the Death Note paper he put in his watch before he lost his memories; and manipulating Rem, who also dies in the process, to kill both Watari and L.

Light is later nominated by L's investigation team (who are unaware that he is Kira) to act as L, due to the fact that they cannot reveal the death of the real L to the world. Light also takes over the role of L's assistant, Watari. Now able to act as both Kira and L, Light can continue killing criminals while leading the investigation team in circles. His secret identity as L is soon discovered by the Special Provisions for Kira, President David Hoope, and Mello's gang. Light joins the Japanese Police Force's Intelligence Department in April 2009, believing that no one can stop his plans. Near and Mello eventually appear before him, trying to accomplish what L could not: to expose Kira's true identity, and bring him to justice. At this point, according to How to Read 13, Light becomes "overtaken with evil" and possessing "arrogance that came with Kira's power"; Light loses sight of his former self.

In the end, the combined efforts of Mello and Near, combined with a large miscalculation and miscommunication on the part of Mikami and Light, force Light to reveal himself as Kira. In the final clash between Near and Light at a warehouse, all is revealed and the Kira case comes to an end after six long years.

According to the manga, Light's date of death is January 28, 2010. His height and weight are 179 centimeters (the height is 5 feet and 10 inches in the VIZ How to Read) and 54 kilograms (119 pounds), respectively. His blood type is A (see Japanese blood type theory of personality).

Light constantly tries to evade the suspicion of L while both maintaining his identity as "Kira"—the name derived from the Japanese pronunciation of the English word "killer"—and cleansing the world of crime. The fact that he is a genius also adds to his notion that only he is fit to judge humanity and steer it on a proper moral course.