In Tokyo, a disaffected high school student named Light Yagami stumbles upon the "Death Note," a mysterious black notebook with a deadly power. The notebook allows its owner to end anyone's life as long as they know the target's true name and face. Initially skeptical, Light quickly grasps the immense power the Death Note grants him and begins using it to eliminate high-profile Japanese criminals and later international criminals. Just five days after finding the notebook, Light encounters Ryuk, a shinigami (death god) and the previous owner of the Death Note. Ryuk, invisible to those who haven't touched the notebook, reveals that he dropped it into the human world out of sheer boredom and finds amusement in Light's actions.As criminals around the world succumb to inexplicable accidents and heart attacks, the global media dubs the mysterious murderer "Kira" (a transliteration of the word "killer" in Japanese). Interpol, seeking to apprehend Kira, enlists the help of a brilliant consulting detective known as L. Deducing that Kira operates from Japan, L strategically manipulates Light into revealing his location in the Kanto region by using a decoy. Enraged by this deception, Light vows to eliminate L, whom he sees as a major obstacle to his plans. L suspects that Kira possesses inside knowledge of the Japanese police investigation, which is led by Light's father, Soichiro Yagami. To investigate the possibility of a familial connection between Kira and the investigation team, L assigns FBI agents to monitor the families of those involved, ultimately leading him to designate Light as the prime suspect.Around this time, Light graduates from high school and enters college. L recruits Light to join the Kira Task Force, where both try to outmaneuver each other in a high-stakes game of cat and mouse.Actress and model Misa Amane obtains a second Death Note from a shinigami named Rem and makes a deal for shinigami eyes, which enable her to see the names of anyone whose face she looks at, at the cost of half her remaining lifespan. Misa becomes infatuated with Light and uncovers his identity as the original Kira. However, Light's intentions with Misa go beyond romance; he plans to use her shinigami eyes to discover L's true name. L deduces that Misa is likely the second Kira and detains her. To save Misa, Light orchestrates a complex scheme involving the temporary loss of their Death Note memories and the passing of the Death Note to a less morally conflicted individual, Kyosuke Higuchi of the Yotsuba Group. After regaining their memories, Light and Misa resume their campaign to eliminate criminals.Rem, the shinigami who loves Misa, realizes that Light's plan all along was to have Misa sacrifice herself to kill L, as a shinigami cannot directly take action to save a human's life. Rem kills L to protect Misa, and Light obtains her Death Note. The task force conceals L's death and agrees to let Light act as the new L, with the investigation seemingly at a standstill. However, crime rates continue to drop as Light, now operating as both L and Kira, faces no imminent threat of capture.Four years later, cults worshipping Kira have emerged. Two young men, raised as potential successors to L, come to the forefront: Near and Mello. Mello joins the mafia, while Near collaborates with the US government. Mello kidnaps Director Takimura, whom Light subsequently kills. In retaliation, Mello kidnaps Light's sister and arranges a trade for the Death Note, using it to kill most of Near's team. A shinigami named Sidoh enters the human realm to reclaim his notebook and ends up assisting Mello. Light attempts to locate Mello's hideout, resulting in the death of Soichiro during the mission.Mello and Near share information, and Mello kidnaps Mogi, handing him over to Near. Kira's supporters launch an attack on Near's group, but they manage to escape. Aizawa, a member of the task force, becomes suspicious of Light and meets with Near. As suspicion falls once again on Misa, Light entrusts Misa's Death Note to a fervent Kira supporter, Teru Mikami. Light also appoints newscaster Kiyomi Takada as Kira's public spokesperson. Near has Mikami under surveillance, and Aizawa's suspicions are confirmed. Realizing that Takada is connected to Kira, Mello kidnaps her. Takada kills Mello but is subsequently killed by Light. Near arranges a meeting between Light and the remaining members of the Kira Task Force. Light attempts to have Mikami use the Death Note to kill Near and the task force, but Mikami's Death Note is a fake, replaced with a decoy by Near. Reviewing the names Mikami had written, they discover that Light's name is missing, conclusively proving that Light is Kira. Light is gravely injured in a confrontation and pleads with Ryuk to write the names of everyone present. However, Ryuk fulfills his promise to Light from the day they met and writes Light's name in the Death Note, leading to Light's demise.One year later, the world has returned to normal, but members of the Kira Task Force grapple with the question of whether they made the right decision. Meanwhile, new cults worshipping Kira begin to emerge, led by a woman who resembles Misa. Three years later, Near, now assuming the role of the new L, receives news of a new Kira's appearance. Learning that this new Kira randomly kills people, Near dismisses the new Kira as "boring" and not worthy of pursuit, as he believes no human can surpass Light's legacy.