Death Note Rules

[Sain After Dark]

If you lose the Death Note or have it stolen, you will lose ownership unless you retrieve it within 490 days.

If you have traded the eye Power of a god of death, you will lose the eye Power as well as the memory of the Death Note once you lose ownership. At the same time, the remaining half of you life will not be restored.  

[Sain After Dark]

You may lend the Death Note to another person while maintaining ownership.
Subletting it to yet another person is possible too.

The borrower of the Death Note will not be followed by a god of death.
The god of death always remains with the owner of the Death Note.
Also, the borrower cannot trade the eyesight of the god of death.  

[Sain After Dark]

When the owner of the Death Note dies while the note is being lent, its ownership will be transferred to the person who is holding it at that time.

If the Death Note is stolen and the owner is killed by the thief, its ownership will automatically be transferred to the thief.  

[Sain After Dark]

When the same name is written on more than two Death Notes the note which was first filled in will take effect, regardless of the time of death.

If writing the same name on more than two Death Notes is completed with a .6 second difference, it is regarded as simultaneous, the Death Note will not take effect and the individual written will not die.