Light (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.
L's suspicions are momentarily subdued, but he does not discard the possibility that Light may be Kira and decides to meet him in person. At the college entrance exams, Light notices a mysterious and eccentric student staring at him.
In a bid to profile Light's behavior, L challenges him to a game of tennis. L asks him some questions regarding the Kira case and invites him to help the investigation. The two then receive news that Light's father has had a heart attack.
As the Kira investigation team discusses the disappearance of Naomi Misora, Sakura TV broadcasts an audio tape allegedly from Kira. To prevent Kira from gaining public support, L demands that the broadcast be stopped.
In a plan to remove all suspicions from himself, Light tells L that he thinks he may be Kira subconsciously and asks to be confined. Light's father believes it is also a good idea to be confined to a cell as well as he cannot risk his emotions getting the better of him. In confinement, Light gives Ryuk the order to have his memory wiped, leaving L confused now that his two suspects both register as sincerely innocent.
L and Soichiro stage a stunt in which Light's father attempts to kill Light and then himself out of shame. Seeing Light and Misa's reactions to it, L intervenes and announces that he no longer suspects them of being Kira.
The third Kira sets his eyes on Misa after meeting her. While Misa takes a break from meeting the Yotsuba Group, Rem contacts her. Misa is able to see the shinigami, but her memories of being the second Kira do not return.
L and Light, watching from the investigation team building, wonder whom Higuchi (seemingly alone) is talking to. L wonders if it's a shinigami. With Rem beside him, Higuchi - frantic to kill Matsuda - takes "the deal" to become unstoppable.
The team arrests Higuchi for being Kira and causing multiple murders. Inspecting Higuchi's Death Note, team members who touch it abruptly discover that shinigami do exist, and when Light takes the Death Note from L, his memory returns.
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.
New investigator Near steps forward, a central figure in the SPK, an American organization trying to catch Kira without relying on L (whom they know is a fake). Near, aware of the existence of Death Notes, wants to get his hands on one, but a challenge to his efforts comes from his orphanage rival, Mello, who throws a curve into Near's efforts by having his underworld thugs kidnap Japanese Police Director Takimura, ready to trade him for a Death Note.
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.
Star newscaster Kiyomi Takada becomes Kira's spokesperson to the world (after Mikami "deletes" Demegawa). 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.
Near, along with the SPK, meets Light and the task force at a warehouse for the final showdown. To everyone's shock, Near reveals that Kira's follower, Mikami, is at the warehouse and is writing everyone's name in the Death Note.