Death Note, which is the title of the cartoon and symbolizes the theme of the work, is a notebook used by envoys to kill humans, and can only be killed by knowing the real name and face of a human. The envoy, Ryuk, who was skeptical of the decaying envoy, drops Death Note into the human world for a purpose close to play, and the main character, high school student Raito Yagami, accidentally picks it up.
Realizing that Death Note is really killing people, Leito agonizes and decides to use it for the world and begins to kill criminals all over the world. Meanwhile, when a meeting was held at Interpol over the death of many criminals for abnormal reasons, L, dubbed the "world's best detective," declared that he would jump into the case, leading to a mystery brain fight between Leito and L.