In Tokyo, an intelligent yet disaffected high-school student named Light Yagami finds the “Death Note”, a mysterious black notebook which can kill anyone as long as the user knows both the target’s name and face. After verifying that the notebook works and initially being terrified of its god-like abilities, Light begins to consider the possibilities of the Death Note’s abilities and sets out to create a utopian world without crime, killing numerous high-profile Japanese criminals, before eventually targeting international criminals and felons around the world. Five days after discovering the notebook, Light is visited by Ryuk, a “Shinigami,” beings inspired by the Japanese god of death and the Death Note’s previous owner. Ryuk, who is invisible to anyone who has not touched the Death Note, reveals that he dropped the notebook into the human world out of boredom and is amused by Light’s actions.
As numerous criminals and convicts around the world begin to die of inexplicable freak accidents and heart attacks, the global media begin to believe that a single mastermind is responsible for the mysterious murders and name him “Kira”, the Japanese transliteration of the word: “killer”, who is both feared and beloved by the public and law enforcement agencies. Hoping to apprehend Kira, Interpol requests the assistance of an enigmatic and highly esteemed international consulting detective, known as L, who has cracked numerous crime cases around the world, to assist them in the investigation. After deducing that Kira is based in Japan, L stages a TV broadcast in which he tricks Light into revealing that he is in the Kanto region of Japan by manipulating him to kill a decoy. Humiliated, Light vows to kill L, whom he views as obstructing his plans. L quickly deduces that Kira has inside knowledge of the Japanese police’s investigation, which is led by Light’s father, Soichiro Yagami. Under the suspicion that “Kira” could have familial connections with the members of the “Kira” investigation, L assigns a team of FBI agents to monitor the families of those connected with the investigation, but Light outmaneuvers and kills them all. Nonetheless, L picks up enough hints to designate Light as the prime suspect. Around this time, Light graduates from high school to college. L recruits Light into the Kira Task Force, with both trying to get the other to reveal crucial information.
At this point, a famous model/actress named Misa Amane gains a second Death Note from a Shinigami named Rem. Misa makes a deal with Rem for Shinigami eyes, which allows her to kill knowing only the face at the cost of half her lifespan. Misa commits numerous murders, sends taped recordings to the police, and eventually uncovers Light’s identity as the original Kira. Infatuated with Light, she demands Light be her boyfriend. Although he does not love Misa, Light agrees, intending to use Misa’s Shinigami eyes to discern L’s true name. However, before she can do so, L deduces that Misa is likely the second Kira and detains her. Rem, who has feelings for Misa, threatens to kill Light if he does not find a way to save Misa. Light arranges a scheme in which he and Misa temporarily lose their memories of the Death Note, and has Rem pass the Death Note to a less morally driven individual, Kyosuke Higuchi of the Yotsuba Group. Now with no knowledge of the Death Note, Light wholeheartedly joins the investigation. Together, Light and L deduce Higuchi’s identity, arrest him, and discover the existence of the Death Notes and the Shinigami. When they touch the Death Note, Light and Misa regain their memories, and Light kills Higuchi with a piece of the Death Note, regaining possession of the book. However, L casts suspicion on Misa, forcing Rem to murder L to save her. Rem dies in the process, as it is forbidden for Shinigami to prevent humans from dying. The task force agrees to cover up L’s death and appoint Light as the new L. The investigation stalls as a result.
Four years later, crime rates worldwide have massively dropped, but cults have arisen which adore Kira. Two intelligent young men, who were raised as potential successors to L, are revealed: Near and Mello. Both are aware that L is dead, and thus consider Light, the current L, a prime suspect. Mello, along with the Mafia’s assistance, kidnaps Light’s sister, resulting in his father’s death during the rescue mission. As suspicion starts to fall again on Misa, Light passes Misa’s Death Note to a fervent supporter of Kira, Teru Mikami. He also appoints a well-known newscaster, Kiyomi Takada as Kira’s public spokesperson. Realizing that Takada is connected to Kira, Mello kidnaps her. Takada kills Mello with a hidden page of the Death Note but is killed by Light in order to dispel suspicions. Shortly after, Near deduces Mikami’s connection to Kira and arranges a meeting between Light and the current Kira Task Force members. Light seizes the chance to have Mikami kill Near as well as all the task force members. However, Mikami’s Death Note fails to work. It is revealed that Near had replaced Mikami’s Death Note with a decoy. Perusing the names Mikami had written down, only Light’s is missing, which proves Light is Kira. A scuffle breaks out during which Light is grievously wounded. Ryuk, realizing that Light will spend the rest of his life in prison, writes down Light’s name in his Death Note—as he had promised to do at the beginning of the story.