The Task Force ( タスクフォース, Tasukufōsu) later called the Japanese Task Force, is the primary organization searching for Kira.
The Task Force is created by Ryuzaki after he deduces that Kira is in Japan and is the only organization within the country that is searching for Kira. The existence of the organization is not made public, and the names and personal information of all of the members are kept secret. After Ryuzaki's death, Light Yagami heads the organization and begins operating under the title of L.
The NPA initially has many members assigned to the Kira case. As it becomes clear that anyone searching for Kira will be in great danger, nearly every officer chooses to leave. The small number who remain are asked to meet with L in person.
In its early days, the Task Force meets at various hotels, arriving at staggered times, until the tower L had built is finished. During this time, L has the homes of two police families bugged; detains Misa Amane, Light, and Soichiro Yagami; and calls in the support of a conman and a thief; all actions that cause tension between L and the officers. When the NPA pulls support from its officers within the Task Force, the members are forced to choose between searching for Kira or staying employed. Shuichi Aizawa leaves after a falling out with L, but he and Hideki Ide use police resources to assist the Task Force in the arrest of Kyosuke Higuchi. The Task Force is in possession of his Death Note for the next five years.
During the time skip, Light takes over the organization and L's identity. When NPA Director Kanichi Takimura and Sayu Yagami are abducted, Aizawa and Ide rejoin the team full-time. The Task Force is present during the storming of the Mafia base, where Soichiro is fatally wounded. After the team has been in contact with Near, Aizawa, and Ide again begin to doubt Light's innocence and keep a close eye on him and Misa. She and Kanzo Mogi are detained by the SPK just prior to Near's invitation for the two organizations to meet in person.
The entirety of the members of both sides are present when the Task Force and the SPK meet in the Yellow Box Warehouse. Teru Mikami writes the names of everyone present in his Death Note, but Near's plan prevails and Light is exposed as Kira, closing the Kira investigation.
|Ryuzaki||L, who goes by the alias Ryuzaki throughout the course of the investigation, is the founder and leader of the Task Force. As L, he is considered in-universe to be the world's greatest detective. His primary objective is to bring Kira to justice at any cost.|
|Light Yagami||Light Yagami is Kira, and he joins the Task Force in order to get close to Ryuzaki and discover his real name. His intelligence is on par with Ryuzaki's.|
|Soichiro Yagami||Soichiro Yagami is Chief of the NPA and Light Yagami's father. He initially leads the group of men who become members of the Task Force.|
|Shuichi Aizawa||Shuichi Aizawa leaves the Task Force after the NPA discontinues funding. He returns before Ryuzaki's death and is one of the first people after the time skip to suspect Light Yagami of being Kira. After the Kira case ends, Aizawa becomes Chief of the NPA.|
|Kanzo Mogi||Kanzo Mogi is one of the most dedicated members of the Japanese Task Force but also one of the most reserved.|
|Touta Matsuda||Touta Matsuda is a young and inexperienced yet dedicated member who wants to solve the case no matter what. He is often chastised by the other Task Force members.|
|Hideki Ide||Hideki Ide helps coordinate the Task Force's efforts and performs actions such as organizing a blockade of police cars.|
|Hirokazu Ukita||Hirokazu Ukita is the most emotional member of the Task Force. He mostly helps Mogi before being killed by the Second Kira.|
|Watari||In addition to being Ryuzaki's handler, Watari is also the supplier of logistics for the Task Force.|
|Aiber||Aiber is a conman hired by Ryuzaki to pose as Eraldo Coil in order to gain the trust of the members of the Yotsuba Group.|
|Wedy||Wedy is a cat-burglar hired by Ryuzaki for her infiltration skills, which are used to plant bugs in the Yotsuba Group Headquarters.|
|Yamamoto||Yamamoto joins the task force one year after Light's death. He has his doubts about the existence of murder notebooks and shinigami. He is also a drinking buddy of Matsuda's.|
|Sanami||Appearing only in the live-action movies, Sanami is the sole female on the investigation team. She tends to Misa during her captivity in the second movie. She is shown to be more skeptical of the methods used by the investigation team, often calling them cruel.|
|Shoko Himura||Appearing only in the live-action TV drama, Himura is the sole woman in the Task Force after being set up as an NPA agent by L. With the goal of obtaining Kira's weapon, she eventually defects from the investigation team to work with Near.|
In other media
After the Kira case is resolved, the Task Force remains active and continues to search for Death Note-related murder.
Ten years after the Kira case, Matsuda is the only remaining member from the original team. New members include Tsukuru Mishima, Sho Nanase, Shin Kuromoto, Uei Uragami, and Captain Junrou Sugawara. All members of the Task Force continue to use aliases, except for Matsuda and Sugawara. Getting onto the team includes passing a polygraph test.
In the Death Note: New Generation episode Mishima's Chapter: Rebirth, the new Kira reveals themself directly to the Task Force by controlling a criminal. Afterword, the Task Force is renamed the Death Note Countermeasure Task Force, and they ask the new L, Ryuzaki, to assist with the case. Ryuzaki initially declines, but in the second episode, Ryuzaki's Chapter: Dying Wish, Ryuzaki agrees.
In Death Note: Light Up the NEW World, the Task Force with Ryuzaki search for the six Death Notes.
In Death Note: The Musical, the Task Force is formed prior to L's involvement. The only members named in the production are Soichiro Yagami and Kanzo Mogi. According to the Korean production credits and the lyrics for "Change the World," the additional members are Ide, Matsuda, Aizawa, and Ukita. Light does not join the Task Force in the musical.
The Task Force sings just one song: Change the World Reprise. After the FBI agents are killed, Soichiro gives the members the option to resign. The Task Force members sing about their obligations to their families, and some of them hope that their families will understand their decisions to risk their lives. At the end of the song, Ide resigns.
After the death of the FBI agents, L has Mogi follow Light. When Light and Misa meet for the first time, Light asks Misa to give him the man's name. Misa is reluctant to do so because he isn't a criminal, but she ends up doing so. Light kills Mogi using the Death Note; Mogi steps out in front of a bus and dies.
The Task Force observes Misa's confinement with L.
Unlike in canon, the Task Force is not present for the final showdown where Light is revealed to be Kira.