Light Yagami é um jovem e brilhante estudante japonês cansado da sua vida cotidiana. Tudo muda quando ele encontra o Death Note, um caderno com poderes ocultos capaz de matar qualquer pessoa no qual tem seu nome escrito em suas folhas. Este caderno pertence a um deus da morte (shinigami), que quando entediado em seu mundo o deixou cair na Terra para assim quebrar sua monotonia. Light, agora sempre acompanhado do shinigami antigo dono desse caderno sombrio, chamado Ryuk, decide usar o item para criar um novo mundo no qual ele seria um "deus", valendo-se da eliminação de criminosos e de todos que ficassem em seu caminho.

Como diversos criminosos recentemente morreram de ataques cardíacos inexplicáveis ​​em todos os cantos do mundo, a Interpol reúne-se para discutir o fenômeno. Incapazes de chegar a uma explicação para isso, o maior detetive do mundo conhecido apenas como L, cuja verdadeira identidade é desconhecida, promete aos representantes da Interpol, atravês de seu contato conhecido como Watari, que encontrara o responsável por estas mortes. O público passa a chamar o suposto vingador de Kira, uma clara referencia a palavra inglesa Killer, que quer dizer assassino, neste momento Light percebe que o mundo esta mudando como ele avia previsto. Ryuk alerta Light que se outro humano tocar o seu caderno este humano poderá vê-lo e ouvi lo, Light então mantem o Death Note em um fundo falso em sua escrivaninha, na qual se incendiaria caso alguém tentasse pegá lo. L então passa a trabalhar com a policia japonesa, e diz a eles que fara um pronunciamento na TV onde sera visto em todo mundo. No dia do pronunciamento L desafia Kira, então Light não exita em matá lo. Quando o homem cai morto sobre a mesa o verdadeiro pronunciamento começa, então o verdadeiro L diz que seu dublê era na verdade um condenado, e também revela que o pronunciamento foi visto apenas pelo região de Kanto no Japão, agora L sabendo onde Kira se esconde, uma batalha entre o bem e mal tem inicio.

Ryuk, the Shinigami, or god of death, who dropped the Death Note into the human world, warns Light that someone is on his trail. Light is troubled that he can’t find out the identity of his tracker, and Ryuk suggests an amazing deal...

Light—now known to the world as Kira—tests the Death Note to understand the scope of its powers by killing off six convicts in various ways—and confirms he can control his victims’ actions before they die.

Soichiro Yagami demands to meet with L in person when he finds out that L has secretly brought FBI agents into Japan. Light, meanwhile, has found a way to get those very FBI agents off the case—permanently...

Light meets a woman at the Police Department with an urgent message for the Kira task force. As son of the chief investigator, Light listens to her story, and is startled to discover she may have information that could lead to his arrest.

Light uses the Death Note to try to get rid of the woman who could get him captured, and is shocked when it doesn’t work. Realizing she must have given him an alias, he’s only got minutes to find out her real name before she tells her story to the task force.

L insists on setting up bugs and cameras in the homes of Chief Yagami and Deputy Director Kitamura—whom Raye Penber was tracking. But Light is a step ahead as usual—he knows he’s being watched.

The murders continue, and L grows suspicious of Light’s too-perfect behavior and decides to investigate him on his own. In order to get closer to Light, L enrolls at the same university and reveals himself to be L.

L's suspicion of Light deepens, compelling him to invite Light into the investigation. But then a phone call alerts them that Soichiro Yagami has suffered a heart attack!

With a second Kira now on the loose, L asks Light to join the task force and pose as the real Kira in order to catch the copycat. Light agrees, hoping to divert suspicion from himself. To his surprise, this new Kira has a special ability even Light lacks…

Light goes to Aoyama to discover the identity of the second Kira before L becomes more suspicious. But Misa Amane, the new Kira, uses her unusual gift to find Light before he finds her.

Light and Misa show each other their Death Notes, and Light asks Misa to have her shinigami Rem get rid of L. But Misa asks something of Light in return—to fall in love with her!

Evidence turns up that points to Misa Amane as the second Kira. In an effort to spare her, Rem forces Misa to forfeit her ownership of the Death Note.

Misa is in confinement, though her memories of the Death Note have been completely wiped away. When Light is confined as well, the murders stop and suspicion of Light grows stronger. Then suddenly, the killings resume.

After fifty days of confinement the killings continue, and Misa and Light are released. But L has devised a plan to ensure no more murders occur, and has Light's father, Soichiro, take the two for a ride that may be their last.

Though L is still suspicious, Light and Misa, their memories of being Kira wiped clean, return to headquarters, where Light notices a strange connection between the recent Kira killings and the Yotsuba Group.

Matsuda, the task force member assigned to watch Misa, is eager to distinguish himself, and while on a job with Misa, he decides to do a little snooping on his own at the Yotsuba Group’s Tokyo headquarters.

L's team discovers that the Yotsuba Group meet in secret to discuss the elimination of individuals who are troublesome to their company, and concludes that Kira must be one of the eight executives. Can Light posing as L ferret out the right one?

The Task Force uses Misa as a way to get closer to the Yotsuba corporation. But things get complicated when Rem tries to communicate with her.

Thanks to Misa, the Task Force now knows the identity of the new Kira and L plans an elaborate scheme to smoke him out of hiding.

L, Light and Misa watch from the investigation team building and wonder who he is talking to. L wonders if Higuchi is talking to a shinigami. Rem convinces Higuchi to go to the station, but she has her own selfish motives for doing so.

While Higuchi is finally captured, Light inadvertently regains his memories as Kira.

Light, his memory recovered, orders Misa to begin killing after Higuchi dies. The Shinigami Rem realizes that everything is going according to Light's plan, and that L will arrest Misa as Kira-unless Rem acts quickly.

After L's death, the world needs a new great detective. Is Wammy's house, where L comes from, able to find a new super detective who can complete L's hunt for Kira?

A new investigator steps forward-Near, a central figure in the SPK, an organization that is trying to catch Kira without relying on L. Near is aware of the existence of the Death Notes and wants to get his hands on one.

Light, acting as L, reveals to Near that his sister Sayu has been kidnapped by someone wanting to trade her for the Death Note. Near finds out that the trade will happen in Los Angeles and promises to help, while secretly planning to steal the Death Note and capture Kira.

Mortified over allowing the Death Note to fall into Mello's hands in order to save his daughter, Soichiro puts himself into harm's way in order to get it back.

Mello busts into SPK headquarters to retrieve a photograph of himself to make sure he won't be killed by Kira. In exchange for Near giving him the picture, Mello drops an important hint about the Death Notes: some of the rules are fake.

Near contacts the Japanese task force and determines that Kira is among their members. He asks for insider information, and Aizawa, beginning to doubt Light, responds. Near suspects that the new L is really Light Yagami and that Light is Kira.

Star newscaster Kiyomi Takada becomes Kira's spokesperson to the world, after Demegawa is deleted by Mikami, and she just so happens to have been Light's girlfriend in college. Aizawa's suspicions about Light grow.

Near goes to Japan, allegedly as bait for Kira. Following Light's instructions, Takada asks Mikami to send her five pages of the Death Note. She tells him that he will continue his work in a fake book made to look like the real one.

Aizawa figures out what's going on and tells Near, who already knows about the notes. Near instructs Aizawa to continue watching Light, and then puts in motion a plan to separate Misa from Light.

Light and Near agree upon a meeting place for the final confrontation. A key player is kidnapped and the end results are shocking.

The Japanese Task Force and the SPK finally meet at YellowBox Warehouse on January 28th. However, a third party has come to the warehouse as well, on Kira's orders to kill everyone else there.

Though Mikami has written all the investigators' names in the Death Note, a minute passes and everyone is still alive. Near seizes Mikami's Death Note, and all is at last revealed.