Human World

The Human World is Earth. Earth within the Death Note universe is identical to that of "real life" in both appearance and life forms. Every aspect of the Death Note universe (excluding Death Notes and Shinigami) is intended to mirror that of "real life".

Humans
Humans within the story are biologically identical to humans in "real life". Any change made to a human through the Death Note is considered to be a supernatural event. Humans who gain Shinigami Eyes, have their life-span extended, or have their life-span shortened do so through supernatural events, not through a change in their biological makeup. Humans that are affected by a Death Note (i.e. their name is written in it) will without a doubt die if the name is written under the Rules of the Death Note. This will happen regardless of the previous health of the victim (i.e. a healthy person will die if their name is written in the Death Note).

Organizations
All organizations that exist in "real life" are assumed to exist within the Death Note universe. Many of these organizations have roles within the story line. These organizations are: There are also organizations that exist solely within the Death Note universe. These organizations are:
 * The United Nations
 * The International Criminal Police Organization (ICPO or Interpol)
 * The National Police Agency (NPA)
 * The Japanese Police Force
 * The Federal Bureau of Investigation (FBI)
 * The Criminal Investigation Agency (CIA)
 * The Mafia
 * The Japanese Task Force
 * The Special Provision for Kira (SPK)
 * Wammy's House
 * Yotsuba
 * Sakura TV